[runtime] Align defaults and schema validators to v1.1.0

[GsCommand]

Motivation

• The runtime was fabricating fallback x402 metadata and resolving receipt schema URLs for v1.0.0, while the route surface has already moved to v1.1.0, so runtime-local defaults and validators must be updated to match the protocol surface.
• Keep the change minimal and local to the runtime layer so signing identity, canonicalization, and verification logic remain untouched.

Description

• Updated the receipt schema URL builder so receiptSchemaUrlForVerb points at ${SCHEMA_HOST}/schemas/v1.1.0/... instead of v1.0.0 and adjusted the shared schema preload list to load _shared files from v1.1.0 (file: server.mjs).
• Changed the fabricated fallback x402 values in the verb handler (success and error paths) to use version: "1.1.0" and entry: "x402://<verb>agent.eth/<verb>/v1.1.0" (file: server.mjs).
• Added a focused unit test that exercises the fabricated-default path on the v1.1.0 route and asserts the emitted fallback x402 is 1.1.0-aligned (file: runtime/tests/runtime-signing.test.mjs).
• No changes were made to signing identity selection, key handling, canonicalization, or /verify design beyond pointing schema validation at the v1.1.0 schema URLs.

Testing

• Ran npm run check which completed successfully with no syntax errors.
• Ran npm run test:unit which executed the runtime unit tests including the added test and all tests passed.
• The added test asserts both the fabricated x402 defaults and that schema validation fetches target v1.1.0 schema paths when schema=1 is exercised.

---

Codex Task