feat(app): open local file references at the referenced line

Mark absolute Markdown links and inline-code relative paths as file
references, resolve them against the originating message cwd, and open
them in the configured editor. Local links no longer navigate the SPA
away from the running renderer.

The canonical transcript assembly projected messages down to seven
fields, so cwd and session_id never reached the renderer. Both are added
to SessionDetailMessage: cwd because the working directory can change
mid-session, session_id because it scopes which roots a reference may
resolve inside. The main process derives those roots from the database
rather than trusting anything the renderer sends.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

packages/core/src/session-detail.ts

@@ -19,6 +19,8 @@ export interface SessionDetailMessage {
   text: string | null;
   content_type: string | null;
   is_meta: 0 | 1;
+  session_id: string | null;
+  cwd: string | null;
   turn_duration_ms: number | null;
 }
 
@@ -365,6 +367,10 @@ function assembleTranscriptRecords(records: Iterable<TranscriptRecord>): Session
           text: record.text,
           content_type: record.content_type,
           is_meta: record.is_meta,
+          // Both kept per message, not per session: the working directory can change
+          // mid-session, and the session id scopes which roots a file reference may resolve in.
+          session_id: typeof record.session_id === 'string' ? record.session_id : null,
+          cwd: typeof record.cwd === 'string' ? record.cwd : null,
           turn_duration_ms: typeof (record as MessageRecord & { turn_duration_ms?: unknown }).turn_duration_ms === 'number'
             ? (record as MessageRecord & { turn_duration_ms: number }).turn_duration_ms
             : null,