ipc: a seed_event method, step-up gated, refused by the store (V-518)

The pattern detector needs four events for one action+object spread by at
least two hours before it proposes a routine. The only writer in the tree is
a fact write at time.Now(), so V-43, V-46, V-247 and V-254 all stopped at the
same missing step. This is the wire half of the seam that unblocks them.

The request takes a fact — key, value, timestamp — not an event, so
pattern.Extract runs for real on the daemon side and a key the extractor
ignores seeds nothing. The response says which of those happened, because a
caller that assumed a seed always yields an event would read four silent
successes as a broken detector.

AuthStepUp, the same rung as mutating the tool allowlist, and not because
backdating is privileged in the usual sense: every other write records when
something happened and this one asserts it. StoreAPI refuses outright — the
method needs the daemon's detect-and-propose step, and a direct store caller
would write a fact and quietly skip it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011x5DgnExQ5XZy8TZPs5bot

internal/ipc/coreapi.go

@@ -110,6 +110,13 @@ type RoutineAPI interface {
 	// loop takes the schedule from there — no reminder is created (Vikunja #366).
 	AcceptProposedRoutine(ctx context.Context, id int64) error
 
+	// SeedEvent writes a backdated fact and runs extraction and detection over
+	// it, so a proposal can be produced in one sitting rather than over real
+	// days (Vikunja #518). See SeedEventReq for why this exists and what keeps
+	// it shut. Daemon-computed, like MorningStatus — the store adapter refuses
+	// it, because the detect-and-propose step lives in mavend.
+	SeedEvent(ctx context.Context, req SeedEventReq) (SeedEventResp, error)
+
 	// MorningStatus returns each configured morning routine's current
 	// checklist state (see internal/morning): active today/now, which items
 	// are done, which are still missing.