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/harness/scenario.go

@@ -25,11 +25,23 @@ type ScenarioPresets struct {
 }
 
 type ScenarioPreset struct {
-	Name       string            `json:"name"`
-	Argv       []string          `json:"argv"`
-	Env        map[string]string `json:"env,omitempty"`
-	WorkingDir string            `json:"working_dir,omitempty"`
-	Shell      bool              `json:"shell,omitempty"`
+	Name           string                  `json:"name"`
+	Argv           []string                `json:"argv"`
+	Env            map[string]string       `json:"env,omitempty"`
+	WorkingDir     string                  `json:"working_dir,omitempty"`
+	Shell          bool                    `json:"shell,omitempty"`
+	IdleDetection  *ScenarioIdleDetection  `json:"idle_detection,omitempty"`
+}
+
+// ScenarioIdleDetection mirrors preset.IdleDetection so scenarios can
+// configure per-strategy idle detection for fake agent presets.
+type ScenarioIdleDetection struct {
+	Strategy           string            `json:"strategy,omitempty"`
+	IdleThresholdMS    int               `json:"idle_threshold_ms,omitempty"`
+	TitleStatusMap     map[string]string `json:"title_status_map,omitempty"`
+	PermissionPatterns []string          `json:"permission_patterns,omitempty"`
+	ThinkingPatterns   []string          `json:"thinking_patterns,omitempty"`
+	ErrorPatterns      []string          `json:"error_patterns,omitempty"`
 }
 
 type ScenarioScript struct {