docs(spec): bump version to 0.12

BREAKING: subsumes the four normative changes landed in ADR-0001..0004 on
this branch:

- JSON Schema Dialect framing (ADR-0001): derivation compatibility applies
  whether the derived schema uses `allOf` + `$ref` or re-declares parent
  fields directly; finality guard determined from the chained `$id` alone.
- `x-gts-traits-schema` as a JSON Schema subschema (ADR-0002): value MAY be
  object/`true`/`false`; the registry composes all declarations along the
  `$id` chain via `allOf` into a single effective trait-schema, so
  descendants no longer need to repeat ancestor trait-schemas.
- Trait completeness keyed on `x-gts-abstract` (ADR-0003): completeness is
  enforced at registration on non-abstract types (not only leaves), against
  the materialized effective traits object.
- Trait-value merge via JSON Merge Patch (RFC 7396) along the `$id` chain
  (ADR-0004): descendant last-wins, nested objects merge recursively,
  arrays replace wholesale, `null` deletes; cross-descendant locking moves
  from a GTS-specific immutability rule to standard JSON Schema `const`
  in `x-gts-traits-schema`.

Conformance tests (in particular `tests/test_op13_schema_traits_validation.py`
cases asserting "override MUST fail") and reference implementations must be
updated to the new semantics in a follow-up.

Signed-off-by: Aviator 5 <ai.agent.tor@gmail.com>

Author: aviator5

README.md

@@ -1,5 +1,5 @@
-<!-- gts-spec-version: 0.11 -->
-> **VERSION**: GTS specification draft, version 0.11
+<!-- gts-spec-version: 0.12 -->
+> **VERSION**: GTS specification draft, version 0.12
 
 # Global Type System (GTS) Specification
 
@@ -112,6 +112,7 @@ See the [Practical Benefits for Service and Platform Vendors](#51-practical-bene
 | 0.9 | Add `x-gts-final` and `x-gts-abstract` schema modifiers; enforce final/abstract semantics in OP#6 and OP#12 |
 | 0.10 | BREAKING: terminology unified around GTS Type / GTS Instance; rename API fields `schema_id` → `type_id` (also `old_schema_id`/`new_schema_id`/`to_schema_id`/`selected_schema_id_field`); rename API field `is_schema` → `is_type` (type-definition vs instance discriminator); `type_id` MUST be a GTS Type Identifier or `null` — no longer falls back to JSON Schema dialect URL; rename endpoints `/validate-schema` → `/validate-type`, `/schemas` → `/types`; rename OP#12 'Schema vs Schema Validation' → 'Type Derivation Validation'; rename OpenAPI components `ValidateSchemaRequest` → `ValidateTypeRequest`, `SchemaRegister` → `TypeRegister`; rename example directories `examples/**/schemas/` → `examples/**/types/` (file extensions `.schema.json` retained); add Terminology section |
 | 0.11 | Introduce term **GTS Type Schema** as the canonical definition of a GTS Type; remove the standalone `Schema` term from Terminology; rewrite `GTS Type` entry to name the abstract registered entity; rename `GTS Type Registry` → `GTS Registry` (registry now scopes both Type Schemas and well-known Instances). **Conformance tests for reference implementations** also updated: rename API endpoints `/validate-type` → `/validate-type-schema` and `/types` → `/type-schemas`; rename OpenAPI components `TypeRegister` → `TypeSchemaRegister`, `ValidateTypeRequest` → `ValidateTypeSchemaRequest`; rename request field `TypeSchemaRegister.schema` → `TypeSchemaRegister.type_schema`; rename helper `validate_type` → `validate_type_schema`. |
+| 0.12 | BREAKING: frame GTS Type Schemas as a **JSON Schema Dialect** over Draft-07 — derivation compatibility (§3.2, OP#12) applies whether the derived schema uses `allOf` + `$ref` or re-declares parent fields directly; finality guard (§9.11) is determined from the chained `$id` alone (ADR-0001). **Reframe `x-gts-traits-schema` as a JSON Schema subschema** (object, `true`, or `false`); the registry composes all `x-gts-traits-schema` declarations along the `$id` chain via `allOf` into a single effective trait-schema — descendants no longer need to repeat ancestor trait-schemas (ADR-0002). **Trait completeness keyed on `x-gts-abstract`**: completeness is enforced at registration on non-abstract types (not only leaves); the materialized effective traits object (defaults applied) is validated against the effective trait-schema (ADR-0003). **Trait-value merge replaced with JSON Merge Patch (RFC 7396)** along the `$id` chain — descendant last-wins at scalar/array/`null` leaves, nested objects merge recursively, arrays replace wholesale, `null` deletes the key (intended fallback to the trait-schema's `default` via materialization); cross-descendant locking moves from a GTS-specific immutability rule to standard JSON Schema `const` in `x-gts-traits-schema` (ADR-0004). |
 
 ## Terminology