chat: tag OpenCode sessions with officer metadata (cwd) + filter lists by it

OpenCode has no per-session directory (every session runs in the fixed server's cwd),
so sessions from every context (/chat pwd, email account, project) all landed in one
list. Now each session is tagged on creation with its logical cwd via the free-form
session `metadata`: { officer: { cwd } } — API-settable, round-trips on list+detail,
never touched by opencode core (confirmed by source dive + live test).

- client.createSession(metadata?) sends `metadata`; adds OfficerSessionMeta + officerMeta() helper.
- send-opencode tags new sessions with { officer: { cwd } } (the resolved chat cwd).
- websocket: pass the full resolved cwd for every context (not just non-/chat).
- listOpenCodeSessions(cwd?) filters by metadata.officer.cwd; chat.ts passes the request cwd.

Verified live: sessions tagged with distinct cwds list only under their own cwd.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/servers/api/chat/chat.ts

@@ -40,7 +40,7 @@ chatRouter.get('/sessions', async (ctx) => {
   const email = ctx.get('user').email;
   const cwd = cwdOf(ctx, email);
   const claude = listClaudeSessions(email, cwd).map((s) => ({ ...s, harness: 'claude' as const }));
-  const opencode = await listOpenCodeSessions();
+  const opencode = await listOpenCodeSessions(cwd);
   const sessions = [...claude, ...opencode].sort((a, b) => b.updatedAt.localeCompare(a.updatedAt));
   return ctx.json({ sessions });
 });