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/server.ts

@@ -135,6 +135,7 @@ import {
   registerFileRoutes,
   registerScheduledRoutes,
   registerHookEventRoutes,
+  registerStatusTelemetryRoutes,
   registerSystemRoutes,
   registerCaseRoutes,
   registerSessionRoutes,
@@ -811,6 +812,7 @@ export class WebServer extends EventEmitter {
     registerFileRoutes(this.app, ctx);
     registerScheduledRoutes(this.app, ctx);
     registerHookEventRoutes(this.app, ctx);
+    registerStatusTelemetryRoutes(this.app, ctx);
     registerSystemRoutes(this.app, ctx);
     registerCaseRoutes(this.app, ctx);
     registerSessionRoutes(this.app, ctx);
@@ -1121,6 +1123,13 @@ export class WebServer extends EventEmitter {
     if (settings.showMultiMonitorButton === true) {
       html = html.replace(' btn-multimonitor--hidden', '');
     }
+    // Plan-usage chip: carries `header-plan-usage--hidden` by default (App
+    // Settings → Display → "Plan Usage Limits"); reveal by stripping the marker
+    // class when the user enabled it, so the chip paints in the right state on
+    // every normal reload (the client toggles the same class live on save).
+    if (settings.showPlanUsageLimits === true) {
+      html = html.replace(' header-plan-usage--hidden', '');
+    }
     // Detached single-session ("solo") window: inject the target session id so
     // the client can enter solo mode even if a (network-first) service worker
     // later serves a cached shell. The client primarily detects solo mode from