Add idle-state classifier and Solo-parity timer tools

Classifies every running child as idle/working/thinking/permission/error
using one of three pluggable strategies (output_activity,
osc_title_stability, osc_title_status) plus optional regex promoters
applied to the tail of recent output. State and last-match reason are
exposed via MCP on ProcessInfo and get_process_status. Per-preset
configuration lives on a new preset.IdleDetection block with bundled
defaults for the first-party claude/codex/opencode presets.

OSC title plumbing is exposed as Emulator.Title(), polled from the
session pump after each emulator write so title-change activity feeds
into the classifier without an extra cgo callback.

The MCP timer surface expands to match Solo: timer_set,
timer_fire_when_idle_any/all, timer_cancel, timer_pause, timer_resume,
timer_list. timer_wait is now a thin wrapper that shares the same
manager so it shows up in timer_list while pending. Timer bodies are
delivered to the owner process through the existing
InjectAsOrchestrator path. Top-level (non-agent) callers can attach
timers to a specific process via owner_process_id; omitting it grants
universal cancel/pause/resume/list privileges.

The sidebar gains a state glyph per process row and appends a
nearest-timer indicator when one is pending or paused.

Tests: idle_test.go covers the classify() pure function across the
three strategies and regex promotion; timers_test.go covers the
manager. Harness scenarios cover output_activity, osc_title_stability,
osc_title_status, and regex promotion, plus timer_set delivery,
cancel, pause/resume, idle_any-on-transition, idle_all-pending, and
idle_all-already-satisfied. A new wait_until_mcp harness step type
polls an MCP method until an assertion holds.

internal/preset/preset.go

@@ -40,9 +40,42 @@ type Preset struct {
 	Shell bool `json:"shell,omitempty"`
 
 	// Agent-only. SPEC §10.
-	MCPInjection     *MCPInjection `json:"mcp_injection,omitempty"`
-	ReadySignal      *ReadySignal  `json:"ready_signal,omitempty"`
-	ChromeTrimHints  []string      `json:"chrome_trim_hints,omitempty"`
+	MCPInjection     *MCPInjection  `json:"mcp_injection,omitempty"`
+	ReadySignal      *ReadySignal   `json:"ready_signal,omitempty"`
+	ChromeTrimHints  []string       `json:"chrome_trim_hints,omitempty"`
+	IdleDetection    *IdleDetection `json:"idle_detection,omitempty"`
+}
+
+// IdleDetection configures steady-state idle classification for an
+// agent preset. Independent of ReadySignal (which is startup-only).
+// All fields are optional; when the whole block is nil the runtime
+// falls back to output_activity with a 2s threshold.
+//
+// Strategy selects the primary signal:
+//   - "output_activity": ms since last PTY output (Claude, OpenCode).
+//   - "osc_title_stability": ms since last OSC 0/2 title change
+//     (Codex, Amp — title changes mean activity).
+//   - "osc_title_status": substring-match the current title against
+//     TitleStatusMap (Gemini — title carries a status word).
+//
+// Promoter patterns are applied on top of the strategy. They run
+// against the recent ring-buffer tail; the first match wins in
+// error > permission > thinking precedence and promotes the state
+// over whatever the strategy returned.
+type IdleDetection struct {
+	Strategy        string `json:"strategy,omitempty"`
+	IdleThresholdMS int    `json:"idle_threshold_ms,omitempty"`
+
+	// TitleStatusMap maps a (case-insensitive) substring of the OSC
+	// title to a state. Only meaningful for "osc_title_status".
+	// Allowed values: "idle", "working", "thinking", "permission", "error".
+	TitleStatusMap map[string]string `json:"title_status_map,omitempty"`
+
+	// Output regex promoters. Compiled at load time; bad patterns are
+	// surfaced as warnings and skipped.
+	PermissionPatterns []string `json:"permission_patterns,omitempty"`
+	ThinkingPatterns   []string `json:"thinking_patterns,omitempty"`
+	ErrorPatterns      []string `json:"error_patterns,omitempty"`
 }
 
 // MCPInjection covers the strategies SPEC §10 enumerates plus
@@ -196,6 +229,15 @@ func ensureDefaults(base string) error {
   "argv": ["claude"],
   "mcp_injection": { "kind": "flag", "flag": "--mcp-config" },
   "ready_signal": { "idle_ms": 1000 },
+  "idle_detection": {
+    "strategy": "output_activity",
+    "idle_threshold_ms": 2000,
+    "permission_patterns": [
+      "Do you want to proceed\\?",
+      "❯ 1\\. Yes",
+      "1\\. Yes, and don't ask"
+    ]
+  },
   "chrome_trim_hints": [
     "^Welcome to Claude Code",
     "^/help for help",
@@ -220,6 +262,10 @@ func ensureDefaults(base string) error {
     "format": "toml"
   },
   "ready_signal": { "idle_ms": 1000 },
+  "idle_detection": {
+    "strategy": "osc_title_stability",
+    "idle_threshold_ms": 2000
+  },
   "chrome_trim_hints": [
     "^OpenAI Codex",
     "^\\s*model:",
@@ -243,6 +289,10 @@ func ensureDefaults(base string) error {
     "var": "OPENCODE_CONFIG_CONTENT"
   },
   "ready_signal": { "idle_ms": 1000 },
+  "idle_detection": {
+    "strategy": "output_activity",
+    "idle_threshold_ms": 2000
+  },
   "chrome_trim_hints": [
     "^\\s*█",
     "^\\s*opencode v",