cliamp moves into the plugin, and the platform loses its last music file

The owner read the code and asked why `plugins/music/api/router.ts` was three
lines importing `@@/api/music/router` — platform code that knows the string
'music'. He was right, and tracing it found the justification was hollow.

The chain: server.tsx:20 imported the cliamp relay's two exports, which are
used only on commented-out lines; so the relay's functions were never invoked;
so its call to getMusicServerWsUrl never ran; and the file's other export,
getMusicServerUrl, had no consumers at all. A dead import held a music-named
file in the platform, and I documented that as a "seam" last night after
checking the import existed and stopping there.

Everything cliamp now lives in plugins/music/cliamp/:

  sidecar/music/{cliamp-ws,pulse-audio}.ts, asoundrc, the test
  api/cliamp/relay.ts
  apps/FileBrowser/{CliampPanel,AudioStreamPlayer}.tsx

src/servers/sidecar/music/, src/servers/api/cliamp/ and src/servers/api/music/
are gone. server.tsx has no cliamp import, provider name, handler entry or
route. The platform contains no file named for music or cliamp.

Two of the things that moved were live, not inert.

The file browser's `Play` context-menu item, on any audio file or folder, set
?play= and rendered a cliamp terminal pointed at /api/cliamp/ws — a route that
upgraded into a handlers entry that was commented out, so handlers[provider]!
asserted non-null on undefined. Using that menu item crashed the socket
handler. Removed: the action, the layout, the panel wiring and both menu
entries. Verified the routes now 404 rather than crash.

That closed the totality drift as a side effect. server.tsx's route table and
its handlers map agree again for the first time since 2026-08-13, and
registry.test.ts now asserts it rather than pinning the hole.

The proxy is built in the plugin now, and its prefix is DERIVED. It was the
literal '/api/music', which the proxy uses to strip characters off the path —
correct only because mountPrefix returns /music for a first-party publisher.
The same plugin published by anyone else mounts at /api/p/<publisher>/music and
would have forwarded /alice/music/stream to a sidecar expecting /stream. A
latent bug only third parties would ever hit, and a quiet violation of the rule
that mountPrefix is the one function allowed to know about provenance. Offscale
has the identical hardcode and still needs it.

Still open there: appName is passed as a literal, because a plugin's router
cannot see its own directory name — the platform imports the module and reads
`router`, so there is nowhere to inject it. The fix is a factory the installer
calls with the plugin's identity.

Plugin backend coupling is down to 7 imports, all of them "a plugin talks to
its host": data-path, sidecar/connect, sidecar/protocol, officer-url, the
manifest type, officerdb/db and the users.id FK. Nothing music-shaped left.

bunx tsgo clean. 797 tests, 787 pass, same 7 pre-existing failures. Verified
live: manifest 200, favorites 200, stream 206, /api/cliamp/ws 404.

plugins/music/PLUGIN.md

@@ -34,30 +34,62 @@ scripts/             the reindex CLI, which talks to the sidecar port directly
 Offscale left nothing behind. Music leaves three, and calling them seams rather than loose ends only
 means each one is written down with what would close it.
 
-### 1. cliamp — out of scope by decision
+### 1. cliamp — parked in the plugin, not left in the platform
 
 `cliamp` and `cliamp-audio` are a _second_ playback path: the `cliamp` TUI run on the server, with its
-terminal and its PulseAudio null sink piped to the browser. The owner's call was that it is the least
-important part of music and not worth blocking the extraction on.
+terminal and its PulseAudio null sink piped to the browser. Out of scope by the owner's decision.
 
-It was already inert before any of this — the two sockets are declared in `server.tsx`'s route table and
-upgrade into `handlers` entries that are commented out. So:
+**All of it now lives in `./cliamp/`** — moved 2026-08-15, in two passes on the same day:
 
-- `src/servers/sidecar/music/` still holds `cliamp-ws.ts`, `pulse-audio.ts`, `asoundrc` and
-  `cliamp-ws.test.ts`. **Untouched.**
-- This plugin's sidecar still serves those sockets, so it imports both modules from
-  `@@/sidecar/music/`. A plugin importing platform code is ordinary; the reverse would not be.
-- `src/servers/api/cliamp/relay.ts` stays, and it is what keeps the next item alive.
+```
+sidecar/music/{cliamp-ws,pulse-audio}.ts, asoundrc, cliamp-ws.test.ts   →  cliamp/
+api/cliamp/relay.ts                                                     →  cliamp/relay.ts
+apps/FileBrowser/{CliampPanel,AudioStreamPlayer}.tsx                    →  cliamp/
+```
 
-### 2. `src/servers/api/music/router.ts` — kept alive by the relay
+`src/servers/sidecar/music/`, `src/servers/api/cliamp/` and `src/servers/api/music/` are **gone**, and
+`server.tsx` has no cliamp import, provider name, handler entry or route left.
 
-`relay.ts` imports `getMusicServerWsUrl` from it. So the platform's proxy could not move, and this
-plugin's `api/router.ts` **re-exports it** rather than building a second one.
+Two things went with it that were live rather than inert:
 
-That is not laziness. `createSidecarProxy` learns its port from a one-shot `music:server` event and
-subscribes at import. Two proxies would mean two subscribers, both working today, and a `503` on the
-first reconnect where only one of them happened to be listening — the same class of failure as the
-install-order bug offscale found, and just as invisible from reading.
+- **The file browser's `Play` action.** A context-menu item on any audio file or folder set `?play=`,
+  which rendered a cliamp terminal panel pointed at `/api/cliamp/ws` — a route that upgraded into a
+  `handlers` entry that was commented out, so `handlers[provider]!.open(ws)` asserted non-null on
+  `undefined`. **Using that menu item crashed the socket handler.** The action, its layout, its panel and
+  its two menu entries are removed; the components are parked here.
+- **The two socket routes.** They now 404. Verified live.
+
+That closed the totality drift as a side effect: `server.tsx`'s route table and its `handlers` map agree
+again, which they had not since 2026-08-13. `registry.test.ts` keeps an assertion on it.
+
+**What it takes to bring cliamp back:** a plugin owning a websocket. `server.reload({ routes })` is proven
+and never called. A platform gap, not a music one.
+
+### 2. ~~`src/servers/api/music/router.ts`~~ — deleted, and the reason it existed was nothing
+
+The proxy was constructed in PLATFORM code that knew the string `'music'`, and this plugin's
+`api/router.ts` merely re-exported it. The stated reason: `api/cliamp/relay.ts` imported
+`getMusicServerWsUrl` from it, so it could not move.
+
+That reason was three layers of nothing:
+
+- `server.tsx:20` imported the relay's two exports — **used only on commented-out lines**
+- so the relay's functions were never invoked, and its call to `getMusicServerWsUrl` never ran
+- and the file's other export, `getMusicServerUrl`, had **no consumers at all**
+
+A dead import held a music-named file in the platform. The proxy is now built in
+`plugins/music/api/router.ts`; the relay takes its URL from there.
+
+**And the prefix is derived rather than written.** It was the literal `'/api/music'`, which the proxy uses
+to strip characters off the path. That is correct only because `mountPrefix` returns `/music` for a
+first-party publisher — the same plugin published by anyone else mounts at `/api/p/<publisher>/music` and
+would have forwarded `/alice/music/stream` to a sidecar expecting `/stream`. A latent bug only third
+parties would ever hit, and a quiet violation of the rule that `mountPrefix` is the one function allowed
+to know about provenance. It now calls `mountPrefix`.
+
+`[open]` `appName` is still a literal there, because a plugin's router cannot see its own directory name —
+the platform imports the module and reads `router`, so there is nowhere to inject it. The fix is
+`api/router.ts` exporting a factory the installer calls with the plugin's own identity.
 
 ### 3. The player — the one open judgement call, and it is decided