nudge: poke an idle chat session on a timer, never a working one

for an agent left running overnight. it is told to record blockers and carry
on rather than wait for a human, and mostly it does — but a turn that ends
leaves it idle until someone types, and at 3am nobody does.

a script rather than a queue job, deliberately. the platform has no recurring
scheduler and no way to put a prompt into a live session — `pushTurn` has
exactly one caller, the chat websocket — so this would be real work in the
queue engine AND the chat api, done tonight, in a repository another agent is
currently working in. instead it talks to the same two doors a browser does
and changes nothing in the platform. if the loop is worth keeping, it belongs
in the queue with a real trigger, and this is what that would replace.

the one rule is that it never interrupts work: `isGenerating` is checked
immediately before speaking and a working session is skipped silently. the
point is to restart a stopped agent, not to hurry a busy one.

`?all=1` on the session list, because without it the list is scoped to the
owner's home and an agent started in a project directory is simply absent —
which this would have read as "the session is gone" and stopped the night.

mints its own owner token: it runs on the box, as the owner, and a token
pasted into a shell is a token in shell history. `--max` defaults to 12, so a
loop nobody is watching ends on its own.

package.json

@@ -11,6 +11,7 @@
     "preinstall": "node -e \"var v = +process.versions.node.split('.')[0]; if (v < 22) { console.error('Node 22 or newer required (got ' + process.versions.node + '). Run: nvm use 22'); process.exit(1); }\"",
     "gen:index": "bun run ./scripts/gen-index.ts",
     "fix:env": "bun run ./scripts/fix-env.ts",
+    "nudge": "bun run --env-file=.env ./scripts/nudge-agent.ts",
     "doctor": "bun run --env-file=.env ./scripts/doctor.ts",
     "secret:set": "bun run --env-file=.env ./scripts/secret-set.ts",
     "notify:test": "bun run --env-file=.env ./scripts/notify-test.ts",