fix(subagent-watcher): discover subagents via agent-*.meta.json (CC format change)

Claude Code changed its subagent on-disk format (~2026-06-14): TUI Task
subagents now write `agent-{id}.meta.json` ({agentType,description,toolUseId})
into the session's `subagents/` dir and no longer reliably write a per-agent
`agent-{id}.jsonl` transcript there. The watcher discovered agents ONLY by
`.jsonl`, so it tracked zero — subagent windows and the monitor's "N TRACKED"
showed nothing.

- Add `registerAgentMeta()`: discover from the meta sidecar (description from
  meta.description/agentType), prefer a sibling `.jsonl` transcript when present
  (richer), never tail a meta file.
- Initial scan + directory watcher now handle `.meta.json` alongside `.jsonl`.
- Tests: 2 new cases (meta-only discovery; prefer-.jsonl-when-present).
  Verified e2e against a real ~/.claude/projects fixture.

Known follow-ups (not in scope): meta-only agents have no per-agent transcript
to tail (no live tool-call feed, status stays 'active'); workflow agents under
`subagents/workflows/{wf}/agent-*.jsonl` are still missed by the flat scan.

Also adds the README screenshot tooling used to surface this:
- capture-real-overview.mjs: DSF=2 + ?nowebgl crisp path (DOM renderer avoids
  the WebGL glyph-doubling at deviceScaleFactor>1).
- capture-readme-real.mjs: real-instance desktop-scene capture (dashboard/
  monitor/subagent) for an isolated beta seeded from prod settings.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/capture-real-overview.mjs

@@ -89,8 +89,13 @@ const main = async () => {
     [SKIN, PLAN_USAGE, FONT]
   );
 
-  console.log(`Loading ${BASE} ...`);
-  await page.goto(BASE, { waitUntil: 'domcontentloaded' });
+  // At DSF>1, xterm's WebGL renderer draws glyphs at ~2x (see DSF comment above).
+  // The app honors a `?nowebgl` URL param that switches to xterm's DOM renderer,
+  // which respects devicePixelRatio correctly — so DSF=2 + nowebgl yields a crisp
+  // 2x (retina) capture at the TRUE font size. Auto-enable it whenever DSF>1.
+  const url = DSF > 1 ? `${BASE}${BASE.includes('?') ? '&' : '?'}nowebgl` : BASE;
+  console.log(`Loading ${url} (DSF=${DSF}) ...`);
+  await page.goto(url, { waitUntil: 'domcontentloaded' });
   await page.waitForFunction(() => window.app && window.app.terminal, { timeout: 20000 });
   await sleep(1500);