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.

CHANGELOG.md

@@ -7,6 +7,40 @@ loosely follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 ## [Unreleased]
 
 ### Added
+- Per-child idle-state classifier with five states (`idle`, `working`,
+  `thinking`, `permission`, `error`) and three pluggable strategies:
+  `output_activity` (claude / opencode defaults), `osc_title_stability`
+  (codex), and `osc_title_status` (gemini-style status-in-title agents).
+  Optional `permission_patterns` / `thinking_patterns` / `error_patterns`
+  regexes promote a base state when matched against the tail of recent
+  output. State and last-match reason are exposed via MCP on
+  `ProcessInfo` and `get_process_status` (`idle_state`, `idle_reason`).
+- New `idle_detection` block on `preset.Preset` for setting the strategy
+  threshold, title-to-state map, and promoter regex lists. Bundled
+  defaults are shipped for the first-party claude / codex / opencode
+  presets.
+- Sidebar now renders a state glyph per process row (`○` idle, `●`
+  working, `◐` thinking, `?` permission, `✕` error) and, when a process
+  has a pending or paused timer, appends a nearest-timer indicator
+  (`⏱ 12s` or `⏸ paused`).
+- MCP timer surface expanded to match Solo's tool set: `timer_set`,
+  `timer_fire_when_idle_any`, `timer_fire_when_idle_all`, `timer_cancel`,
+  `timer_pause`, `timer_resume`, `timer_list`. Idle-aware timers
+  registered against already-idle children fire synchronously
+  (`status: already_satisfied`) for `idle_all`, and report
+  `already_idle` / `waiting_on` arrays so callers can introspect the
+  watch set. Timer bodies are delivered to the owner process via the
+  same orchestrator-injection path as `send_message`.
+- Timer tools accept an explicit `owner_process_id` so top-level
+  (non-agent) callers — including the harness MCP client — can attribute
+  timers to a specific process. Omitting it treats the caller as the
+  orchestrator with universal cancel / pause / resume / list privileges.
+- libghostty-vt `Title()` accessor on the emulator surface, polled from
+  the session pump so OSC 0/1/2 title updates feed into the classifier
+  without a callback round-trip.
+- Harness `wait_until_mcp` step type that re-runs an MCP method until an
+  assertion (Equals / Contains) holds or the timeout elapses. Used by
+  the new idle / timer scenarios.
 - User-created top-level command processes now survive a patterm
   restart. Each spawn (palette form, command preset, or MCP
   `spawn_process` with `kind=command`) writes a record to
@@ -64,6 +98,9 @@ loosely follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   after a child program disables mouse tracking.
 
 ### Changed
+- `timer_wait` is now a thin wrapper over the shared timer manager
+  (`timer_set` semantics). Existing callers see no behavioural change;
+  the timer is visible in `timer_list` while it's pending.
 - CLI flag parsing switched from Go's stdlib `flag` to `spf13/pflag`.
   `--project` (and the internal `--socket` / `--identity` /
   `--scenario` / `--patterm-bin` flags) are now the only accepted form