fix: eye icon follows /clear to the new Claude conversation (#76)

Interactive Claude CLI never emits session_id on stdout, so the
Session's _claudeSessionId stayed pinned to the pre-/clear jsonl and
the last-response viewer kept showing the old conversation.

Two complementary update paths:

- Session.adoptClaudeSessionId() — public setter mirroring the existing
  no-op-if-same guard. Called from POST /api/hook-event when Claude Code
  hooks carry data.session_id (works once hooks are configured).

- /api/sessions/:id/last-response now resolves the active id from
  ~/.claude/history.jsonl before reading the transcript. This is the
  only source-of-truth that does not require hooks, and we intentionally
  don't write hooks into arbitrary user repos.

History scan filters out sessionIds held by other Codeman sessions in
the same cwd, and validates via jsonl mtime to avoid inheriting a dead
prior session's id.

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

src/session.ts

@@ -484,6 +484,15 @@ export class Session extends EventEmitter {
     return this._claudeSessionId;
   }
 
+  // Adopt a Claude conversation ID observed from an external source (e.g. hook
+  // payload). In interactive PTY mode Claude CLI emits no JSON to stdout, so
+  // `_handleJsonMessage` never sees `session_id`; hooks are the only signal
+  // that conveys a post-/clear conversation switch.
+  adoptClaudeSessionId(newId: string): void {
+    if (!newId || newId === this._claudeSessionId) return;
+    this._claudeSessionId = newId;
+  }
+
   /** The tmux session name, if the session is running inside a mux */
   get muxName(): string | null {
     return this._muxSession?.muxName ?? null;