Desktop app session list doesn't include sessions started from the CLI

Title: Desktop app session list doesn't include sessions started from the CLI

Body:

The Desktop app's session list (Recents sidebar / list_sessions) and the CLI's claude --resume picker are backed by two different indexes, and they don't reconcile.

Repro:

1. Start several sessions from the terminal (claude) across a few different repos over a few days.
2. Run claude --resume in the terminal — all of those sessions show up.
3. Open the Desktop app's Code tab and check the session list / Recents.
4. None of the above appear. Only sessions that were started from, or previously opened in, the Desktop app itself show up.

What I think is happening:

• claude --resume reads session transcripts directly off disk (~/.claude/projects/**/*.jsonl), so it sees every session regardless of which surface created it.
• The Desktop app's session list appears to be backed by its own tracked index (session IDs prefixed local_, linked via claude://claude.ai/epitaxy/...), which only contains sessions the Desktop app itself is aware of — not a scan of the same transcript files the CLI reads.

Expected: Since CLI and Desktop share the same ~/.claude config, hooks, skills, and MCP settings, I'd expect them to share session history too — a session started in one should be resumable from the other, and both should show the same Recents list.

Impact: Users who move between terminal and Desktop (e.g. quick terminal session while away from the Desktop app) lose visibility into that work from the other surface. Recent, actively-referenced sessions silently don't show up.

Suggested fix: Have the Desktop app's session list also enumerate local transcript files under ~/.claude/projects (the same source --resume uses), merging them with its own tracked index, rather than relying solely on its own backend-tracked session records.