refactor: consolidate ~70 scattered constants into 6 new config files (phase 6)

Create 6 domain-focused config files in src/config/ to centralize operational
tuning knobs that were scattered across 15+ source files:

- server-timing.ts: SSE batching, state debounce, scheduled runs, error recovery
- auth-config.ts: session TTL, rate limits, hook timeout
- tunnel-config.ts: QR token rotation, tunnel process lifecycle
- terminal-limits.ts: input length, terminal cols/rows, session name
- ai-defaults.ts: AI model string, idle/plan context limits
- team-config.ts: poll interval, cache sizes

Eliminates all cross-file duplicates:
- AI model string: 5 occurrences → 1 (config only)
- STATS_COLLECTION_INTERVAL_MS: 2 → 1
- timeout: 10000 in hooks-config: 6 → 0 (now HOOK_TIMEOUT_MS)
- MAX_TRACKED_AGENTS shadow: removed, imports from map-limits

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/config/server-timing.ts

@@ -0,0 +1,68 @@
+/**
+ * @fileoverview Web server performance and scheduling constants.
+ *
+ * Controls terminal batching throughput, SSE health checking,
+ * state persistence debouncing, and scheduled run timing.
+ *
+ * @module config/server-timing
+ */
+
+// ============================================================================
+// Terminal & SSE Performance
+// ============================================================================
+
+/** Terminal data batching interval — targets 60fps (ms) */
+export const TERMINAL_BATCH_INTERVAL = 16;
+
+/** Immediate flush threshold for terminal batches (bytes).
+ * Set high (32KB) to allow effective batching; avg Ink events are ~14KB. */
+export const BATCH_FLUSH_THRESHOLD = 32 * 1024;
+
+/** Task event batching interval (ms) */
+export const TASK_UPDATE_BATCH_INTERVAL = 100;
+
+/** SSE client health check interval (ms) */
+export const SSE_HEALTH_CHECK_INTERVAL = 30 * 1000;
+
+// ============================================================================
+// State Persistence
+// ============================================================================
+
+/** State update debounce — batches expensive toDetailedState() calls (ms) */
+export const STATE_UPDATE_DEBOUNCE_INTERVAL = 500;
+
+/** Sessions list cache TTL — avoids re-serializing on every SSE init (ms) */
+export const SESSIONS_LIST_CACHE_TTL = 1000;
+
+// ============================================================================
+// Scheduled Runs
+// ============================================================================
+
+/** Scheduled runs cleanup check interval (ms) */
+export const SCHEDULED_CLEANUP_INTERVAL = 5 * 60 * 1000;
+
+/** Completed scheduled run max age before cleanup (ms) */
+export const SCHEDULED_RUN_MAX_AGE = 60 * 60 * 1000;
+
+/** Session limit retry wait before retrying (ms) */
+export const SESSION_LIMIT_WAIT_MS = 5000;
+
+/** Pause between scheduled run iterations (ms) */
+export const ITERATION_PAUSE_MS = 2000;
+
+// ============================================================================
+// Mux Stats
+// ============================================================================
+
+/** Mux stats collection interval (ms) */
+export const STATS_COLLECTION_INTERVAL_MS = 2000;
+
+// ============================================================================
+// Process Error Recovery
+// ============================================================================
+
+/** Max consecutive unhandled errors before auto-restart */
+export const MAX_CONSECUTIVE_ERRORS = 5;
+
+/** Error counter reset interval — forgives errors after quiet period (ms) */
+export const ERROR_RESET_MS = 60_000;