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/vt/emulator.go

@@ -57,6 +57,11 @@ type Emulator interface {
 	// ActiveScreen reports whether we are on the primary or alternate buffer.
 	ActiveScreen() (Screen, error)
 
+	// Title returns the most recently set window title (OSC 0/2). Returns
+	// an empty string if no title has been set. Used by idle detection
+	// for the osc_title_stability and osc_title_status strategies.
+	Title() (string, error)
+
 	// ScrollViewportTop moves the viewport to the top of the scrollback.
 	ScrollViewportTop() error
 

internal/vt/ghostty.go

@@ -544,6 +544,27 @@ func (e *GhosttyEmulator) Cursor() (CursorState, error) {
 	return CursorState{Col: uint16(col), Row: uint16(row), Visible: bool(visible)}, nil
 }
 
+// Title returns the most recent window title set by OSC 0/2 escape
+// sequences. The libghostty-vt API hands back a borrowed pointer that
+// stays valid only until the next vt_write/reset, so we copy out to a
+// Go string under the same mutex that gates writes. An empty string
+// (len=0) means no title has been set.
+func (e *GhosttyEmulator) Title() (string, error) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	if e.closed {
+		return "", errors.New("vt: emulator closed")
+	}
+	var s C.GhosttyString
+	if rc := C.ghostty_terminal_get(e.term, C.GHOSTTY_TERMINAL_DATA_TITLE, unsafe.Pointer(&s)); rc != C.GHOSTTY_SUCCESS {
+		return "", fmt.Errorf("vt: get title failed: %s", ghosttyResultStr(rc))
+	}
+	if s.ptr == nil || s.len == 0 {
+		return "", nil
+	}
+	return C.GoStringN((*C.char)(unsafe.Pointer(s.ptr)), C.int(s.len)), nil
+}
+
 func (e *GhosttyEmulator) ActiveScreen() (Screen, error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()

internal/vt/ghostty_nocgo.go

@@ -24,6 +24,7 @@ func (e *GhosttyEmulator) SerializeVT() ([]byte, error)    { return nil, errStub
 func (e *GhosttyEmulator) StyledScreenVT() ([]byte, error) { return nil, errStub }
 func (e *GhosttyEmulator) Cursor() (CursorState, error)    { return CursorState{}, errStub }
 func (e *GhosttyEmulator) ActiveScreen() (Screen, error)   { return 0, errStub }
+func (e *GhosttyEmulator) Title() (string, error)          { return "", errStub }
 func (e *GhosttyEmulator) ScrollViewportTop() error        { return errStub }
 func (e *GhosttyEmulator) ScrollViewportBottom() error     { return errStub }
 func (e *GhosttyEmulator) ScrollViewportDelta(int) error   { return errStub }