Phase 6b: a handler's query is @Queries only; drop the signature clauses

The handler-signature `query (vars) [terms] where …` clause and the
`reads`/`writes` clauses overlapped the `@Queries` annotation (and each other):
two ways to attach a query to a handler. Consolidated on the decorator.

  - parse_system no longer parses `query`/`reads`/`writes` clauses; it keeps the
    postfix `@anno(...)` channel and `phase`. A handler's query is the prefix
    `@Queries(these: [...], on: Model)` annotation. Data-access hints are now
    `@Reads(...)`/`@Writes(...)` — absorbed by the generic annotation skipper,
    same parse-and-reserve status the old clauses had.
  - The inline `for (…) in query […] where …` statement is unchanged and still
    covers cross-property constraints / multiple kind filters. `query` stays a
    keyword there (now dispatched via is_id so the vocabulary check sees it).

examples/hello.ludic and examples/qdecl.ludic migrated to `@Queries` (qdecl now
demonstrates a per-property constraint + `on:` tag); outputs unchanged
(4 4 10 3 / 0 3 -2). LANGUAGE.md handler sections rewritten. Vocabulary: drop
`reads`/`writes` from CLAUSE (ludic_syntax.h, grammar, LudicTokens.kt).

Reseeded (21931 lines); C-free fixpoint holds; goldens identical; 17/17;
vocab + doc-fences clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tools/editors/vscode/syntaxes/ludic.tmLanguage.json

@@ -163,7 +163,7 @@
       "patterns": [
         { "name": "keyword.control.ludic", "match": "\\b(if|else|while|for|in|match|machine|become|return|spawn|despawn|enable|disable|where|break|continue|new)\\b" },
         { "name": "keyword.operator.logical.ludic", "match": "\\b(and|or|not)\\b" },
-        { "name": "keyword.other.clause.ludic", "match": "\\b(phase|query|reads|writes|on)\\b" },
+        { "name": "keyword.other.clause.ludic", "match": "\\b(phase|query|on)\\b" },
         { "name": "keyword.other.ludic", "match": "\\b(import|extern)\\b" },
         { "name": "storage.type.ludic", "match": "\\b(program|property|struct|model|enum|ui|const|var|let|fn|handler|entry|state)\\b" },
         { "name": "support.type.primitive.ludic", "match": "\\b(int|fixed|bool|entity|str|ptr|void)\\b" },