feat: live notes — single objective per note replaces multi-track model

Folds the multi-`track:`-array model into one `live:` block per note: a single
persistent objective the live-note agent maintains, plus an optional triggers
object (`cronExpr` / `windows` / `eventMatchCriteria`, each independently
optional). A note is now passive or live — no per-track scopes, no section
ownership contract, no `once` trigger. The agent owns the whole body and makes
patch-style incremental edits per run.

Highlights:
- Schema: `track:` array → single `live:` object (`packages/shared/src/live-note.ts`).
- Runtime: scheduler / event processor / runner under `core/knowledge/live-note/`,
  with split `lastAttemptAt` (every run, drives 5-min backoff) vs `lastRunAt`
  (success only, anchors cycles). `throwOnError` on agent runs surfaces LLM /
  billing failures into `lastRunError`.
- Today.md: regenerated by template v2 (single objective covering overview /
  calendar / emails / what-you-missed / priorities; existing files renamed to
  `Today.md.bkp.<stamp>`).
- Renderer: `LiveNoteSidebar` mounts inside the editor row (no chat overlap,
  auto-closes on note switch); toolbar Radio button becomes a status pill;
  `LiveNotesView` replaces background-agents view.
- Copilot: new `live-note` skill with act-first stance, default folder/cadence
  pickers, and a non-negotiable rule to extend an existing objective rather
  than add a second one. Shared `KNOWLEDGE_NOTE_STYLE_GUIDE` enforces
  terse-and-scannable writing across `doc-collab` and the live-note agent.
- Analytics: `track_block` use-case → `live_note_agent`; trigger
  (`manual` / `cron` / `window` / `event`) becomes the Pass-2 sub-use-case,
  alongside `routing` for Pass 1. Legacy run files with the old value are
  read-mapped via `LegacyStartEvent` so they stay openable in the runs list.

Hard cutover — no back-compat shims for legacy `track:` frontmatter arrays.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -108,7 +108,7 @@ Long-form docs for specific features. Read the relevant file before making chang
 
 | Feature | Doc |
 |---------|-----|
-| Tracks — frontmatter directives that keep a note's body auto-updated (cron / window / once / event / multi-trigger), section-placement model, sidebar UI, Copilot skill, prompts catalog | `apps/x/TRACKS.md` |
+| Live Notes — single `live:` frontmatter block (one objective + optional cron / windows / eventMatchCriteria) that turns a note into a self-updating artifact, panel UI, Copilot skill, prompts catalog | `apps/x/LIVE_NOTE.md` |
 | Analytics — PostHog event catalog, person properties, use-case taxonomy, how to add a new event | `apps/x/ANALYTICS.md` |
 
 ## Common Tasks