make machine-setup.sh and officer-setup.sh actually run on macOS

Both scripts had real macOS branches already — MACOS_SKIP, Xcode CLT, Docker Desktop
detection — but neither had ever run past its own library load on a real Mac, and
verifying that live is what this commit is. This machine is the Mac.

The root cause was the interpreter, not missing OS coverage: macOS's stock /bin/bash is
3.2.57 (Apple stopped shipping newer once bash went GPLv3) and this machine has no newer
one installed. Both scripts used bash 4+/4.3+ syntax with zero version guard, so a real
run died in seconds — declare -A (base.sh, associative array), local -n (packages.sh,
nameref), mapfile (5 sites), ${var,,} (both scripts' own step() — confirmed --only killed
the ENTIRE run), and machine-setup.sh's own pre-flight hard-refused brew outright ("this
script does not implement yet") even once the bash-4 crash was fixed. Each got rewritten
to its bash-3.2-safe equivalent rather than requiring a newer bash and re-executing under
it — nine call sites, a bounded fix, and one less thing that can go wrong before the
script can report what's wrong.

Past that gate, a live probe run (real account/path prompts, killed before Database/
Services could touch this machine's actual state) reproduced a second bug in the first
few seconds: resolve_user_home used getent (Linux/glibc, absent on macOS) with a
hardcoded /home/<user> fallback, so Layout tried `install -d /home/pastilhas` and failed
with "Operation not supported". Fixed with the portable `eval echo ~user` tilde-expansion
idiom, re-ran the same probe, and it correctly created /Users/pastilhas/officerdev/ and
started a real git clone.

Everything else follows the same shape — an unguarded Linux-only tool with a portable or
brew-based macOS equivalent:

  - grep -oP (4 sites: both --list flags, env.sh's tailnet lookup, build.sh's schema
    table count) — BSD grep has no -P at all. Portable ERE+sed where regex was enough;
    jq where the input was already JSON (tailnet lookup) — jq is already an unconditional
    dependency elsewhere in this script, so that's a correctness fix, not just a port.
  - ss (postgres.sh, proxy.sh — is anything listening on this port, and is it bound wide
    enough for NPM's container to reach) — both silently mis-reported on macOS, since the
    "command not found" was swallowed by 2>/dev/null and read as "nothing's listening".
    New shared `listening_addrs()` in officer-setup's base.sh, branching to lsof.
  - getent hosts (proxy.sh's DNS-wait loop) — same silent-failure shape, would have spun
    its full 30-minute timeout regardless of whether the record actually resolved. macOS
    branch uses dscacheutil.
  - stat -c (layout.sh's ownership check) — BSD stat has no -c, confirmed live ("illegal
    option -- c"), and the failure was VISIBLE and made every layout directory report as
    wrong-owner. Portable file_owner() tries -c then falls back to -f %Su.
  - apt-only Postgres client, NodeSource's Debian-only setup script, lazydocker/lazygit's
    installers (one literally named install_update_linux.sh, the other hardcoding
    "_Linux_" into the release asset URL) — each gets a brew branch, formula names
    verified against the live Homebrew catalog rather than assumed.
  - sudo -u "$USERNAME" to become the SAME account the process already is — real on
    Linux, where this whole script runs as root and dropping to the owner needs no
    password; on macOS the process never escalates in the first place, so re-invoking
    sudo for yourself asks for a real password on every call, or fails outright without
    sudo rights. machine-setup's dev.sh had ~10 inline call sites (git, bun, deno, claude,
    opencode, editor detection) rerouted through a new shared run_as_owner(); officer-
    setup's own as_owner() (already the shared entry point there) got the same branch,
    and six direct sudo call sites in build.sh/secrets.sh/services.sh that bypassed it
    were rerouted through it too.

Three things stay Linux-only rather than getting an unverified macOS implementation,
each skipped with a stated reason at the point it would otherwise run: pm2's boot-
persistence hook (needs a launchd plist generated and loaded, not a systemd unit
printed and eval'd — real, separate work), the Tailscale exit-node NIC/sysctl tuning
(no macOS equivalent concept, and advertising a laptop as an exit node is already the
edge case MACOS_SKIP treats it as), and ufw's bridge-to-host firewall rule (pf is a
different rule language entirely, and Docker Desktop's own VM-based networking may not
even have the problem this rule exists to solve — guessing at a firewall rule felt like
the wrong place to be wrong).

Verified: both --list flags print step names instead of a grep usage error. A bounded
officer-setup.sh run (killed before Database) resolved the real macOS home directory,
created the layout with correct ownership, and began a real git clone — cleaned up
after (rm -rf the test directory, the gitignored .setup-progress file, the stray
install-report). machine-setup.sh's pre-flight now reports "Packages: brew" and reaches
the account/path prompts instead of refusing the OS outright. bash -n clean on all 16
files under bash 3.2, the actual interpreter these scripts run under on a Mac.

Not run further live: Database, Secrets, Services and Proxy would mutate this machine's
real state (a live Postgres, a live set of pm2 processes this session runs through) and
were left for a deliberate, supervised run rather than folded into validation.

scripts/setup/machine-setup/machine-setup.sh

@@ -46,7 +46,9 @@ while [[ $# -gt 0 ]]; do
       shift
       ;;
     -l | --list)
-      grep -oP '^step "\K[^"]+' "${BASH_SOURCE[0]}"
+      # Portable ERE + sed rather than GNU grep's -P/\K — BSD grep on macOS has no -P at
+      # all and errors immediately ("invalid option -- P"), confirmed live.
+      grep -E '^step "' "${BASH_SOURCE[0]}" | sed -E 's/^step "([^"]+)".*/\1/'
       exit 0
       ;;
     -h | --help)
@@ -114,15 +116,17 @@ info "Machine:  ${OS_NAME} (${ARCH})"
 info "Packages: ${PM:-none detected}"
 [[ "$IS_WSL" == true ]] && warn "WSL detected — the suspend, logind and boot-hang steps do not apply here"
 
-# Everything below this line is written against apt and systemd. Detection above
-# recognises pacman, dnf and brew so the branches have somewhere to hang, but
-# nothing implements them yet — and running the apt path on Arch would half-build
-# a machine and stop somewhere unhelpful. Refuse clearly instead, and relax this
-# list one entry at a time as each package manager grows a real path.
+# Everything below this line is written against apt and systemd, with real macOS/brew
+# branches threaded through where a Mac needs different behaviour (MACOS_SKIP for whole
+# steps that are server-only, `$OS == macos` for the rest). Detection above also recognises
+# pacman and dnf so THEIR branches have somewhere to hang, but nothing implements those yet
+# — running the apt path on Arch would half-build a machine and stop somewhere unhelpful.
+# Refuse clearly instead, and relax this list one entry at a time as each package manager
+# grows a real path.
 case "$PM" in
-  apt) ;;
+  apt | brew) ;;
   "") fail "Could not find a package manager for '${OS_NAME}'." ;;
-  *) fail "${OS_NAME} uses ${PM}, which this script does not implement yet — apt-based systems only, so far." ;;
+  *) fail "${OS_NAME} uses ${PM}, which this script does not implement yet — apt and brew only, so far." ;;
 esac
 
 ask_machine_role
@@ -404,7 +408,9 @@ fi
 
 step "System update"
 if ! skip; then
-  mapfile -t UPGRADABLE < <(pkg_upgradable)
+  # `mapfile` is bash 4+; macOS's stock bash is 3.2. This is the portable substitute.
+  UPGRADABLE=()
+  while IFS= read -r _line; do UPGRADABLE+=("$_line"); done < <(pkg_upgradable)
 
   echo ""
   info "System update — upgrades installed packages to their latest versions"
@@ -2479,7 +2485,9 @@ EOF
   echo "     which is why git's own core.editor is deliberately not set: git"
   echo "     falls back to \$EDITOR, so setting it here covers everything."
   echo ""
-  mapfile -t EDITORS < <(editor_candidates)
+  # mapfile is bash 4+; macOS's stock bash is 3.2.
+  EDITORS=()
+  while IFS= read -r _line; do EDITORS+=("$_line"); done < <(editor_candidates)
   if ((${#EDITORS[@]} == 0)); then
     warn "no editor found to offer — skipping"
   else