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/public/settings-ui.js

@@ -315,6 +315,7 @@ Object.assign(CodemanApp.prototype, {
     document.getElementById('appSettingsShowFileBrowser').checked = settings.showFileBrowser ?? defaults.showFileBrowser ?? false;
     document.getElementById('appSettingsShowSubagents').checked = settings.showSubagents ?? defaults.showSubagents ?? false;
     document.getElementById('appSettingsShowMultiMonitorButton').checked = settings.showMultiMonitorButton ?? defaults.showMultiMonitorButton ?? false;
+    document.getElementById('appSettingsShowPlanUsageLimits').checked = settings.showPlanUsageLimits ?? defaults.showPlanUsageLimits ?? false;
     // Gesture control lives in the Input section (alongside Local Echo / CJK Input)
     // but is only available when the instance runs with CODEMAN_GESTURE=1 (server sets
     // window.__codemanGestureAvailable). Hide just this item otherwise so the toggle
@@ -1369,6 +1370,7 @@ Object.assign(CodemanApp.prototype, {
       showFileBrowser: document.getElementById('appSettingsShowFileBrowser').checked,
       showSubagents: document.getElementById('appSettingsShowSubagents').checked,
       showMultiMonitorButton: document.getElementById('appSettingsShowMultiMonitorButton').checked,
+      showPlanUsageLimits: document.getElementById('appSettingsShowPlanUsageLimits').checked,
       gestureControlEnabled: document.getElementById('appSettingsGestureControl').checked,
       subagentTrackingEnabled: document.getElementById('appSettingsSubagentTracking').checked,
       subagentActiveTabOnly: document.getElementById('appSettingsSubagentActiveTabOnly').checked,
@@ -1658,6 +1660,7 @@ Object.assign(CodemanApp.prototype, {
         showFileBrowser: false,
         showSubagents: false,
         showMultiMonitorButton: false,
+        showPlanUsageLimits: false,
         // Input
         gestureControlEnabled: false,
         // Feature toggles - keep tracking on even on mobile
@@ -1770,6 +1773,16 @@ Object.assign(CodemanApp.prototype, {
       multiMonitorBtn.classList.toggle('btn-multimonitor--hidden', !showMultiMonitorButton);
     }
 
+    // Plan-usage chip — hidden by default (App Settings → Display → "Plan Usage
+    // Limits"). Server renders the initial state on reload; this handles a live
+    // toggle from a settings save. Marker class (base is display:inline-flex
+    // !important), matching the response-viewer/multimonitor pattern.
+    const showPlanUsageLimits = settings.showPlanUsageLimits ?? defaults.showPlanUsageLimits ?? false;
+    const planUsageChip = document.getElementById('planUsageChip');
+    if (planUsageChip) {
+      planUsageChip.classList.toggle('header-plan-usage--hidden', !showPlanUsageLimits);
+    }
+
     // Notification bell is retired (notifications live in Settings → Notifications
     // + the drawer); keep it hidden regardless of the notification-enabled state.
     const notifBtn = document.querySelector('.btn-notifications');