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/schemas.ts

@@ -158,6 +158,8 @@ export const CreateSessionSchema = z.object({
   effort: effortLevelSchema,
   /** Model override to write to .claude/settings.local.json (e.g., "opus[1m]"). Empty string clears. */
   modelOverride: z.string().max(50).optional(),
+  /** Inject the plan-usage statusLine exporter into the case (App Settings → Display → "Plan Usage Limits"). Claude-only. */
+  statusLineTelemetry: z.boolean().optional(),
   openCodeConfig: OpenCodeConfigSchema,
   codexConfig: CodexConfigSchema,
   /** Resume a previous Claude conversation by its session ID (used for reboot recovery) */
@@ -186,6 +188,37 @@ export const ResizeSchema = z.object({
   viewportType: z.enum(['mobile', 'tablet', 'desktop']).optional(),
 });
 
+/**
+ * Schema for POST /api/status-telemetry
+ * Claude Code statusline payload forwarded by the Codeman-managed statusLine
+ * exporter (see hooks-config.generateStatusLineCommand). Validates only the
+ * subset Codeman displays; unknown keys (session_id, transcript_path, cwd, …)
+ * are stripped by z.object. Auth-exempt like /api/hook-event.
+ */
+const RateLimitWindowSchema = z
+  .object({
+    used_percentage: z.number().optional(),
+    resets_at: z.number().optional(),
+  })
+  .optional();
+
+export const StatusTelemetrySchema = z.object({
+  sessionId: z.string().min(1).max(100),
+  data: z
+    .object({
+      rate_limits: z
+        .object({
+          five_hour: RateLimitWindowSchema,
+          seven_day: RateLimitWindowSchema,
+        })
+        .optional(),
+      context_window: z.object({ used_percentage: z.number().optional() }).optional(),
+      cost: z.object({ total_cost_usd: z.number().optional() }).optional(),
+      model: z.object({ display_name: z.string().max(100).optional() }).optional(),
+    })
+    .optional(),
+});
+
 // ========== Case Routes ==========
 
 /**
@@ -321,6 +354,7 @@ export const SettingsUpdateSchema = z
     showFileBrowser: z.boolean().optional(),
     showSubagents: z.boolean().optional(),
     showMultiMonitorButton: z.boolean().optional(),
+    showPlanUsageLimits: z.boolean().optional(),
     // Input
     gestureControlEnabled: z.boolean().optional(),
     // Claude CLI settings