Give the stage 0 grammar set one home (V-693)

buildRouter held the real set and baselineGrammars in eval_test.go restated it
by hand, in the daemon's order, with its own comment saying so. Three test files
score against the fixture and nothing compared the two lists. They had already
drifted: BareCaptureGrammar went into the daemon with V-557 and never into the
fixture, so every routing measurement since has scored a set nobody runs. That
is the failure CLAUDE.md warns about by name, and a diff test would have caught
it one grammar late.

The list moves to router.StageZeroGrammars in internal/router/stagezero.go, with
the ordering comments, which are the load-bearing part. buildRouter and the
fixture both call it. One list cannot drift from itself.

Measured before and after on the 96-case fixture: classifier+onnx 72/96, 75.0%
intent, 33.3% destination, identical either way, and the deterministic claim and
reach hash ratchets do not move. So the missing grammar cost no measurable
accuracy. That is the point rather than a reprieve: the fixture had been scoring
the wrong set for four days and nothing could say so.

The invariants caveat is deleted, both entries, since V-692 landed the other
guard in the previous commit. The reasoning for both now sits in docs/routing.md
beside the subsystem, which is where a fix's durable record belongs.

Unrelated and pre-existing: TestONNXPersonalBoundary fails on "я рассказывал
тебе про байкал?" (personal 0.9068, world 0.9413) at the merge base too.

internal/router/eval/eval_test.go

@@ -255,35 +255,12 @@ func newBaselineClassifier(t *testing.T, emb router.Embedder) *router.Classifier
 	return cls
 }
 
-// baselineGrammars — the stage-0 rule set in the daemon's order (buildRouter in
-// cmd/mavend/voicewire.go). Split out of newBaselineRouter so the claim
-// measurement can run the same rules one at a time and see which of them
-// contend for the same utterance, which the cascade hides by stopping at the
-// first match.
+// baselineGrammars — the stage 0 rule set the daemon runs, from the one place
+// it is written down (V-693). It used to restate the list by hand, and by the
+// time the guard was written the two had already drifted by one grammar.
+// Kept as a name because the claim measurement reads it as "the baseline set".
 func baselineGrammars(acts router.ActMatcher) []router.Grammar {
-	grammars := router.DefaultGrammars(acts)
-	grammars = append(grammars, router.SystemTimeDateGrammars()...)
-	// Same order as buildRouter (voicewire.go). The fixture is only worth
-	// anything while its grammar set is the daemon's grammar set.
-	grammars = append(grammars, router.AgendaQueryGrammars()...)
-	// After the agenda rules and before the feed and list rules, same as
-	// voicewire.go: "что такое лента" is a definition question and the feed
-	// rule would claim it on the noun alone (V-655). Missing here until V-659,
-	// so the fixture was scoring a grammar set the daemon does not run.
-	grammars = append(grammars, router.WorldQueryGrammars()...)
-	grammars = append(grammars, router.FeedQueryGrammar())
-	// The list side of the same exposure: a phrasing with no possessive in it
-	// ("список дел") routed system and never reached queryTasks (Vikunja #467).
-	grammars = append(grammars, router.TaskListGrammar())
-	grammars = append(grammars, router.ListGrammars()...)
-	grammars = append(grammars, router.ReminderGrammar())
-	grammars = append(grammars, router.PraxisGrammars()...)
-	grammars = append(grammars, router.TaskStatusGrammar())
-	grammars = append(grammars, router.TaskCaptureGrammar())
-	// "расскажи про X" is a world question the model called a fact, and the
-	// rule goes last because it matches on the first word alone (Vikunja #498).
-	grammars = append(grammars, router.NarrativeQueryGrammars()...)
-	return grammars
+	return router.StageZeroGrammars(acts)
 }
 
 // seedOrder — fixed iteration order over the corpus. Not cosmetic: a few