feat: F5.1 server F keeps the shared documents

A new package, packages/server: Hocuspocus 3.4.4 on /sync, a project a
document, refused with a reason when the store has not got it; every update
stored in Postgres as it comes and compacted after 500 updates, a minute of
quiet and when the last person leaves (FOR UPDATE on the row written when
the project is made); the janitor runs only here, at loading and 250 ms
after a change that is not its own; readers change nothing; /healthz; JSON
log. On closing it takes no one new and closes the sockets too (Hocuspocus'
close is a message after which a client signs in again on the same socket).
The tests use real clients against a throwaway Postgres in Docker.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

package.json

@@ -11,7 +11,7 @@
   },
   "scripts": {
     "test": "vitest run",
-    "typecheck": "tsc -b && tsc -p packages/core/test && tsc -p packages/fls/test && tsc -p packages/doc/test && tsc -p packages/protocol/test && tsc -p packages/sim/test && tsc -p packages/sim/browser && tsc -p packages/editor && tsc -p packages/editor/test",
+    "typecheck": "tsc -b && tsc -p packages/core/test && tsc -p packages/fls/test && tsc -p packages/doc/test && tsc -p packages/protocol/test && tsc -p packages/sim/test && tsc -p packages/server/test && tsc -p packages/sim/browser && tsc -p packages/editor && tsc -p packages/editor/test",
     "test:browser": "playwright test",
     "check": "npm run typecheck && npm run test",
     "hooks": "git config core.hooksPath scripts/hooks",