grammar: the last two model calls that were still free text

The replier and the meeting summariser were the two call sites without a
GBNF. Both are exactly the shape that makes a Thinking variant answer with
its reasoning as prose, and neither had anything downstream that could
remove it.

The replier already parses {"response","mood"}, so it now sends the phraser's
grammar for that contract, exported once as phraser.ResponseGrammar so the
two definitions cannot drift.

The summariser stays text-in/text-out. The JSON wrapper is attached and
unwrapped in the daemon's Completer, so internal/capture is unchanged and a
Completer without a grammar still works.

The simulator told routing from phrasing by "has a grammar", which stopped
being true here; it now looks for the intent enum.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/phraser/llmphraser.go

@@ -603,6 +603,11 @@ string ::= "\"" ([^"\\] | "\\" ["\\/bfnrt]){0,1000} "\""
 ws     ::= [ \t\n]*
 `
 
+// ResponseGrammar exposes responseGrammar to the other callers that emit the
+// same {"response","mood"} contract — cmd/mavend's reactive replier, which is
+// parsed by the same two fields. One definition, so the two cannot drift.
+const ResponseGrammar = responseGrammar
+
 // grammar returns the GBNF to attach to a phrasing request, or "" when the
 // operator turned it off.
 func (p *LLMPhraser) grammar() string {