fix(tmux): isolate sessions on a dedicated socket + raise pane nofile limit (fixes new-session crash after tmux upgrade) (#96)

* fix: isolate codeman tmux sessions

* fix(tmux): unify all sessions onto a single dedicated socket

Remove the per-session `tmuxSocket` field that recorded which tmux server
each session lived on (default vs the `codeman` socket). That field was a
persisted cache of physical reality and could drift — causing live sessions
to be wrongly marked dead ("tab shows no session found") and spawning
duplicate "Restored:" tabs.

All Codeman sessions now live on one process-wide socket (`tmux -L codeman`,
overridable via CODEMAN_TMUX_SOCKET), exposed via TmuxManager.muxSocket on
the TerminalMultiplexer interface. reconcileSessions() collapses from a
multi-socket scan (locate / re-pin / cross-socket dedup) to a single
`list-panes` query. loadSessions() strips the obsolete field from on-disk
records so it stops being written back.

Also fix two sibling bare-`tmux` call sites the unification would otherwise
leave broken (same #80 regression class — bare tmux hits the user's default
server and never finds a session on the codeman socket):
- session.ts queryTmuxWindowSize(): add `-L <socket>` (was silently falling
  back to 120x40 on re-attach, losing scrollback)
- session-routes.ts send-key (Shift+Enter / Ctrl+Enter newline): route
  through ctx.mux.muxSocket

SSH chooser scripts (tmux-manager.sh, tmux-chooser.sh) route every tmux call
through `tmux -L $CODEMAN_TMUX_SOCKET`, matching the TS default.

---------

Co-authored-by: Teigen <teigen@TeigendeMac-mini.local>

test/tmux-manager.test.ts

@@ -77,9 +77,24 @@ describe('TmuxManager (unit)', () => {
   });
 
   describe('getAttachArgs', () => {
-    it('should return attach-session args', () => {
+    it('should attach every session through the dedicated Codeman socket', () => {
       const args = manager.getAttachArgs('codeman-abc12345');
-      expect(args).toEqual(['attach-session', '-t', 'codeman-abc12345']);
+      expect(args).toEqual(['-L', 'codeman', 'attach-session', '-t', 'codeman-abc12345']);
+    });
+
+    it('should attach registered sessions on the same dedicated socket (no per-session socket)', () => {
+      manager.registerSession({
+        sessionId: 'some-session',
+        muxName: 'codeman-abc12345',
+        pid: 12345,
+        createdAt: Date.now(),
+        workingDir: '/tmp',
+        mode: 'claude',
+        attached: false,
+      });
+
+      const args = manager.getAttachArgs('codeman-abc12345');
+      expect(args).toEqual(['-L', 'codeman', 'attach-session', '-t', 'codeman-abc12345']);
     });
   });