feat(sidecar): protocol 12 — POST /titles (phase 17)

One more thin forward: the chat titles each player has earned, as a whole
set the plugin swaps in and BetterChat reads on the chat path. perm.sync's
BetterChat styles and chat.say's delivery and format pass through untouched
like the rest of their bodies. PROTOCOL_VERSION moves to 12.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

sidecar/README.md

@@ -57,6 +57,7 @@ still authenticate). Every response carries `X-RustLink-Version`.
 | `GET /feed?since=&limit=` | store | **Oldest first, from a cursor.** For a consumer that must not miss a row. Omitting `since` asks where the end is |
 | `GET /status` | plugin (RPC) | A live round trip. `503` with no plugin, `504` on no reply |
 | `GET /ws` | broadcast | The live feed. Sends `ws.hello` on connect |
+| every later route | plugin (RPC) | One thin forward per command, from `POST /link/confirm` (protocol 3) to `POST /titles` (protocol 12). Each is listed beside its protocol in `src/web.rs`, and its body in `docs/rust-link/PROTOCOL.md` |
 
 The split is the point: the store-backed reads answer while the game is off, which is what lets the
 website render a server list during a wipe or a restart. `/status` is the one route that fails when