neo4j: add TS-prefixed twin node labels (dual-label, graph schema 1.1.0) #65

PROBLEM

The Neo4j projection emits only bare node labels (Application, Module, Class, Interface, Enum, TypeAlias, Namespace, Callable, External, AnonymousCallable, Package, Decorator, CallSite, Attribute, Variable; marker Entrypoint), which a shared multi-language database cannot attribute to TypeScript. This issue adds a TS-prefixed twin label to every node, additively, so downstream queries can namespace by language without breaking any existing consumer.

SCOPE BOUNDARY

Node labels only. Relationship types stay unprefixed (CALLS, HAS_MODULE, …) — their rename is breaking and lands with the v2/CanNode contract (stage 2). Merge labels (Symbol, Module, Package, Decorator, CallSite, Attribute, Variable, Application), uniqueness constraints, keys, and analysis.json are untouched. No in-place migration of existing databases.

GOALS

1. Every NodeLabel in src/build/neo4j/schema.ts declares its TS-prefixed twin (e.g. Callable + TSCallable), and the marker set gains TSEntrypoint alongside Entrypoint; the declarative schema remains the single source of truth.
2. Both writers (cypher.ts snapshot and bolt.ts incremental) stamp both labels on every node; MERGE still targets the unchanged merge label + key.
3. SCHEMA_VERSION → 1.1.0 (additive MINOR per the schema's own rule).
4. Conformance test (test/neo4j-schema.test.ts) covers the twin labels; schema.neo4j.json and the README help block regenerated.

CAVEATS AND KNOWN RISKS

• Dual labels double the label count per node; Neo4j handles multi-labels natively, but any consumer doing labels(n)[0] or exact-set label comparisons will see the new twin — additive, yet worth a release-note line.
• The old branch patch/ts-prefix-neo4j-schema is NOT a starting point: it rewrote catalog.ts, which the refactor(neo4j): consolidate the graph schema into one source of truth (closes #15) #16 consolidation deleted. Re-author against schema.ts; use the branch only as a checklist of touch points.
• Bolt writer batches: ensure the twin label is applied in the same MERGE/SET statement so a crash mid-load never leaves half-labeled nodes.

DEFINITION OF DONE

• On the fixture app, for every declared label L: MATCH (n:L) and MATCH (n:TSL) return identical counts; total relationship count is byte-identical to the pre-change graph.
• Conformance test green; :Application carries schema_version = "1.1.0".
• schema.neo4j.json regenerated and committed; bun run gen:readme clean.

Delivers #8 additively (merge label deliberately stays shared — see the epic's design decisions).

Part of #64