orpc-v2: migrate all six contracts to the v2 route builder

Ticket ID: B3

Parent

#248 — orpc-v2: consolidate fork into everything-dev and migrate platform to oRPC v2 + Effect 4 (epic)

What to build

Stage B, step 3: migrate the six contract files (the api's base contract plus the five plugins' contracts) to the oRPC v2 route builder. Each file preloads the @orpc/openapi route extension (import "@orpc/openapi/extensions/route") so .route carries full OpenAPIMeta. Route paths, input/output schemas, and metadata (tags/summary/description) stay equivalent, and the contract tsconfig type-emission flow must still work.

Acceptance criteria

• All six contracts on the v2 builder with the route extension preloaded
• Generated OpenAPI spec equivalent to pre-migration (ignoring the OAS version field)
• Contract type-emission flow green
• No route/path/shape changes — wire-compatible

Blocked by

• #259 — createPlugin restructure

After #259 is complete, locate the API base contract and five plugin contract files, then read their current builders and the preloaded @orpc/openapi route extension. Migrate all six to the oRPC v2 route builder without changing paths, schemas, or metadata. Verify the generated OpenAPI spec is equivalent and the contract tsconfig type-emission flow is green.