voice/routing: fix time-query misroute (seed collision, threshold, stage-0 grammars)

three bugs causing time queries to land on reminder or fact intent:

- seed collision: query.txt and system.txt shared identical time/date
  seeds (который час, сколько времени), making system intent
  indistinguishable from query intent in centroid space
- threshold (0.35) too low for ONNX embedder — cosine similarities
  cluster 0.5-0.7 for related intents, so Clarify never fired
- reminder centroid contaminated by time-lexicon (every seed has a time
  expression), pulling any time-word utterance toward reminder intent

fixes:
- remove 3 duplicate time/date seeds from query.txt (keep in system.txt)
- DefaultRouterThreshold 0.35 -> 0.55
- stage-0 grammar for напомни/remind me -> IntentReminder, bypasses
  classifier (fixes 'напомни через час' being misrouted to fact)
- stage-0 grammars for time/date system queries (сколько времени,
  который час, какой сегодня день) -> IntentSystem, with Build filter
  to exclude elapsed/duration queries (сколько времени прошло)
- time parser fallback in applyAction for stage-0 reminder matches
  (extractor doesn't run on stage-0 decisions)

internal/config/config.go

@@ -320,7 +320,7 @@ const (
 	DefaultTickInterval     = 60 * time.Second
 	DefaultRepeatInterval   = 5 * time.Minute
 	DefaultAutotuneInterval = 10 * time.Minute
-	DefaultRouterThreshold  = 0.35
+	DefaultRouterThreshold  = 0.55
 	DefaultQueryMinScore    = 0.55
 	DefaultToolTimeout      = 30 * time.Second
 )