feat(desktop): context page deepening — window bar + compact Config + intervention marker + subagent drilldown

Four Context-page enhancements (lane-ctx-deep, F1-F4):

- F1 context window breakdown: replace percentage-only card header with
  a stacked-bar breakdown of input / cached / output token buckets,
  plus a right-side gauge showing the live window occupancy ratio.
- F2 compact Config tab: fold the sprawling profile Config editor into
  a Config tab on the Context page card, with the same yml-leaf
  ordering as the top-of-window profile picker.
- F3 intervention marker: on the intervention timeline, emit a marker
  glyph at each user-intervention row (turn-flow-glyph-style) so the
  card scans as a single stream instead of a header + separate list.
- F4 subagent drilldown: when a turn's tool trace hits a subagent, the
  Trace panel's Config + Output tabs get a second row of Subagent
  Config / Subagent Output tabs immediately below, driven by the same
  fold-in-place shape the parent panel already uses.

4 new renderer modules (compact-config-model / context-window-breakdown /
intervention-timeline / subagent-drilldown), 6 new test files (41 tests,
all node --test style), 4 QA shoot scripts for CDP-driven regression
screenshots.

examples/desktop/scripts/qa-cdp-run-ctx-deep.mjs

@@ -0,0 +1,89 @@
+// Real-machine isolated runner for the lane-ctx-deep shots (task #51).
+// Boots Electron on a private CDP port with a private USER_DATA and
+// DSH_DESKTOP_HOME under $TMPDIR (2026-07-18 postmortem — nothing here
+// touches the user's real ~/.dsh-desktop), then invokes the shot script.
+//
+// Usage: node scripts/qa-cdp-run-ctx-deep.mjs
+
+import { spawn } from 'node:child_process'
+import { existsSync, mkdirSync, writeFileSync, rmSync } from 'node:fs'
+import { resolve, join } from 'node:path'
+import { setTimeout as sleep } from 'node:timers/promises'
+import { tmpdir } from 'node:os'
+
+const WORKTREE = resolve(process.env.DSH_WORKTREE || process.cwd())
+const PARENT = resolve(process.env.DSH_REPO || '/Users/ziya/harness/dsh-desktop-demo')
+const ELECTRON = join(PARENT, 'node_modules/.bin/electron')
+const CDP_PORT = Number(process.env.DSH_CTX_DEEP_PORT || 9285)
+const USER_DATA = join(tmpdir(), 'dsh-ctx-deep-userdata')
+const DSH_HOME = join(tmpdir(), 'dsh-ctx-deep-home')
+const OUTDIR = join(WORKTREE, 'docs/demo-shots')
+const SHOOT_SCRIPT = join(WORKTREE, 'scripts/qa-cdp-shoot-ctx-deep.mjs')
+
+if (!existsSync(ELECTRON)) {
+  console.error(`electron binary not found at ${ELECTRON}`)
+  process.exit(2)
+}
+mkdirSync(OUTDIR, { recursive: true })
+for (const dir of [USER_DATA, DSH_HOME]) {
+  try { rmSync(dir, { recursive: true, force: true }) } catch {}
+  mkdirSync(dir, { recursive: true })
+}
+// Seed a minimal config so onboarding modal stays out of the way. Use
+// echo-jsonrpc (jsonrpc-demo bin) — daemon-demo has been renamed to
+// jsonrpc-demo upstream and the daemon-* config still points at the old
+// path, so echo-jsonrpc is the correct keyless profile today.
+writeFileSync(join(DSH_HOME, 'user-overlay.cordis.yml'), [
+  '# ctx-deep QA seed overlay',
+  'plugins:',
+  `  - "@cordisjs/plugin-include":`,
+  `      path: ${join(WORKTREE, 'config/echo-jsonrpc.yml')}`,
+  '',
+].join('\n'))
+writeFileSync(join(DSH_HOME, 'config.json'), JSON.stringify({ role: 'coding', approvalMode: 'never' }))
+writeFileSync(join(DSH_HOME, '.onboarded'), new Date().toISOString())
+
+const child = spawn(ELECTRON, [
+  `--remote-debugging-port=${CDP_PORT}`,
+  `--user-data-dir=${USER_DATA}`,
+  '--disable-gpu',
+  '--no-sandbox',
+  '.',
+], {
+  cwd: WORKTREE,
+  env: {
+    ...process.env,
+    DSH_DESKTOP_HOME: DSH_HOME,
+    DSH_DEV_ROOT: process.env.DSH_DEV_ROOT || '/Users/ziya/harness/deepseek-harness-dev',
+    DSH_MAXIMIZE: '1',
+    DSH_QA: '1',
+  },
+  stdio: ['ignore', 'pipe', 'pipe'],
+})
+const logs = []
+child.stdout.on('data', d => logs.push(String(d)))
+child.stderr.on('data', d => logs.push(String(d)))
+
+let up = false
+for (let i = 0; i < 40; i++) {
+  await sleep(500)
+  try {
+    const r = await fetch(`http://localhost:${CDP_PORT}/json/list`)
+    if (r.ok) { up = true; break }
+  } catch {}
+}
+if (!up) {
+  child.kill('SIGKILL')
+  console.error('electron did not come up on CDP :' + CDP_PORT)
+  console.error(logs.join(''))
+  process.exit(3)
+}
+
+// Run the shot script against our port.
+const shooter = spawn(process.execPath, [SHOOT_SCRIPT, String(CDP_PORT), OUTDIR], {
+  cwd: WORKTREE,
+  stdio: 'inherit',
+})
+const rc = await new Promise((r) => shooter.on('exit', (code) => r(code)))
+child.kill('SIGKILL')
+process.exit(rc || 0)