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/wire.go

@@ -67,6 +67,7 @@ const (
 	MethodListSpeakers           Method = "list_speakers"
 	MethodForgetSpeaker          Method = "forget_speaker"
 	MethodRecentEvents           Method = "recent_events"
+	MethodSeedEvent              Method = "seed_event"
 
 	// MethodPing — liveness, and the only method that answers in locked mode
 	// without a passkey assertion. It reaches no store, takes no arguments and