soulseek, extracted into plugins/soulseek — the platform half

Seventh extraction, and the first of something that was already dead. Soulseek
had been switched off since 2026-08-13: hono.ts carried the router import and
its PROTECTED_MOUNTS entry commented out, so createSidecarProxy never ran and
registerProxiedPrefix was never called; officer-slskd was not in the ecosystem
at all. Because the permission entry had been reduced to api: [], the totality
check was satisfied and the server booted clean — the UI rendered and every
request 404'd. Worth naming: the boot check proves every MOUNTED prefix has a
permission, and is silent about a feature that mounts nothing.

Also closes a live data hazard: schema.ts had the soulseek export commented
out, so the three tables were absent from the drizzle barrel and bun db:push
would have dropped soulseek_favorites, soulseek_browse_snapshots and
soulseek_browse_dirs on any server holding them. rebuild-soulseek-tree.ts
documented the workaround rather than the problem; deleted with the rest.

The connection stays in core service_connections under service 'slskd' while
the mount is now /api/soulseek. Those differ on purpose.

Test fixtures: slskd was canonical in three app-store tests, the third
extraction running to break them. installer.test.ts now builds a literal
fixture instead of reaching into the catalogue — it pins planSteps, which is
installer logic, and no catalogue entry is both provisioned and members:'none'
any more. catalogue.test.ts and members.test.ts re-anchored to vnc/notify/gitea.

Unrelated but mine: check:theme caught 5 palette classes I introduced in
CommandHQ earlier tonight against a baseline of 0. Converted to bg-success /
bg-warning. check:theme is not part of bun test, which is why the green suite
never showed it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/servers/api/slskd/router.ts

@@ -1,18 +0,0 @@
-import { createSidecarProxy } from '../../sidecar/create-proxy';
-
-// /api/slskd/* — auth, then forward to officer-slskd. No routes of its own and no slskd knowledge:
-// this file must never grow app logic.
-//
-// Covers both slskd's own API (/api/v0/searches, /api/v0/transfers, …) and the sidecar's Officer-owned
-// routes (/_officer/*, features slskd has no concept of). Both are opaque from here; the sidecar injects
-// the slskd API key. The full contract is documented at the top of src/servers/sidecar/slskd/index.ts.
-
-const proxy = createSidecarProxy({
-  name: 'slskd',
-  prefix: '/api/slskd',
-});
-
-export const slskdRouter = proxy.router;
-
-/** Base URL of the sidecar's HTTP server, or null if it hasn't reported in yet. */
-export const getSlskdServerUrl = proxy.getHttpUrl;