feat(events): a trigger can start a run

Rust PLAN_REDESIGNS §14.3.12 (D370), stage 9 of §14.3. A definition's
published version may carry `starts`: a trigger, a condition and a
cooldown. A matching firing creates a run of it, now.

- spec: `starts` validated by the phase gate's own function (same
  grammar, same dormant rule; a dormant start refuses publish), a
  cooldown from 0m to 7d (30m default), at most ten, event.* refused.
- events/starts.js: the emit path's third subscriber, beside dispatch
  and the gate observer. An unverified version starts nothing; one run
  at a time per definition and the cooldown are one conditional UPDATE
  on the new event_trigger_starts table; the occurrence key makes one
  firing reported twice one run. Ignored firings are counted by why.
- event_runs.origin: the firing (trigger, label, time, subject, matched
  condition, declared variables), also on the run.created audit line.
- Editor: a "Started by the game" panel using the gate's condition
  builder, with the ignored-firings line. Run console: "Started because
  ... fired".
- No module contract change and no MODULE_API bump.

Tests: eventStarts (server 21, client 8); eventRunnerSql +7 against a
real MariaDB (75/75); Module-uo proof on uo.champ.boss_up against the
dev database.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

server/src/model/events/eventDefinitions.db.js

@@ -159,6 +159,30 @@ const findSchedulable = async ({ listedOnly = false } = {}) => {
   return rows.map((row) => ({ ...row, version_spec: parseJson(row.version_spec, null) }))
 }
 
+/**
+ * Every `ready` definition whose PUBLISHED version starts on this trigger
+ * (Rust PLAN_REDESIGNS §14.3.12, D370). The emit path's question, asked on every
+ * firing, so it answers in one query and the common answer is no rows.
+ *
+ * Read from the version, never the working copy, for the reason the schedule
+ * expansion is: a start an author is midway through typing must not fire.
+ * `JSON_EXTRACT` over `$.starts[*].on` is an array, or NULL for a version with
+ * no starts, and `JSON_CONTAINS` of NULL is not true.
+ */
+const findStartingOn = async (triggerId) => {
+  const rows = await query(
+    `SELECT d.id, d.title, d.grace_seconds, d.current_version_id,
+            v.spec AS version_spec, v.verified_at AS version_verified_at
+       FROM event_definitions d
+       JOIN event_versions v ON v.id = d.current_version_id
+      WHERE d.state = 'ready'
+        AND JSON_CONTAINS(JSON_EXTRACT(v.spec, '$.starts[*].on'), JSON_QUOTE(?))
+      ORDER BY d.id`,
+    [triggerId],
+  )
+  return rows.map((row) => ({ ...row, version_spec: parseJson(row.version_spec, null) }))
+}
+
 /**
  * One definition by slug, for the PUBLIC event page (Phase 14a).
  *
@@ -206,6 +230,7 @@ module.exports = {
   listPublicBySeries,
   slugTaken,
   findSchedulable,
+  findStartingOn,
   insert,
   update,
   markReady,