feat(usage): plan usage limits header chip via statusLine telemetry

Surface Claude subscription plan usage limits (5-hour rolling + 7-day
weekly: percent used + reset time) in the header, opt-in via App Settings
→ Display → "Plan Usage Limits" (default OFF, no behavior change when off).

A Codeman-managed Claude statusLine exporter forwards the rate_limits JSON
to a new auth-exempt POST /api/status-telemetry (same loopback + hook-secret
gate as /api/hook-event); parsed telemetry broadcasts over SSE
session:statusTelemetry to a header chip (amber >=80%, red >=95%, reset
times on hover). The exporter prints the same summary back as the
in-terminal footer (print-through).

- src/usage-telemetry.ts: pure parser/formatter (epoch-sec -> ms, clamp,
  change signature) + test/usage-telemetry.test.ts
- hooks-config.ts: generateStatusLineCommand + applyStatusLineConfig
  (add/remove; never clobbers a user's own statusLine)
- session-routes.ts: inject gate (Claude-only, Codeman-managed cases),
  driven by create-payload statusLineTelemetry (session-ui.js)
- schemas.ts: StatusTelemetrySchema + showPlanUsageLimits + payload field
- frontend: header chip, applyHeaderVisibilitySettings toggle,
  renderIndexHtml strip, _onSessionStatusTelemetry handler

Schema empirically confirmed against Claude Code 2.1.177 (Claude Max):
only five_hour/seven_day windows exist (no Opus-weekly field); rate_limits
is absent before the first API response and for non-subscriber auth. Design
+ verification method in docs/usage-limits-display-plan.md.

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

src/web/routes/session-routes.ts

@@ -45,7 +45,7 @@ import {
   validatePathWithinBase,
 } from '../route-helpers.js';
 import { AUTH_COOKIE_NAME } from '../middleware/auth.js';
-import { writeHooksConfig, updateCaseModel, stripCaseEnvKeys } from '../../hooks-config.js';
+import { writeHooksConfig, updateCaseModel, stripCaseEnvKeys, applyStatusLineConfig } from '../../hooks-config.js';
 import { generateClaudeMd } from '../../templates/claude-md.js';
 import { imageWatcher } from '../../image-watcher.js';
 import { getLifecycleLog } from '../../session-lifecycle-log.js';
@@ -297,6 +297,14 @@ export function registerSessionRoutes(
       await updateCaseModel(workingDir, body.modelOverride || null);
     }
 
+    // Plan-usage statusLine exporter (App Settings → Display → "Plan Usage
+    // Limits"). Claude-only, and only inside Codeman-managed cases (never
+    // arbitrary user repos, which may carry a hand-authored statusLine). Adds or
+    // removes our exporter so toggling the setting off cleans up on next create.
+    if ((body.mode ?? 'claude') === 'claude' && workingDir.startsWith(CASES_DIR + '/')) {
+      await applyStatusLineConfig(workingDir, body.statusLineTelemetry === true);
+    }
+
     // Check OpenCode availability if requested
     if (body.mode === 'opencode') {
       const { isOpenCodeAvailable } = await import('../../utils/opencode-cli-resolver.js');