feat(rpc): add target policy, protocol schemas, and tagged errors

- Add normalizeLoopbackTarget() with loopback-only URL validation
- Add JSON-RPC response decoder with schema validation
- Define 8 tagged errors using Data.TaggedError
- 20 tests covering target policy and protocol decoding
- Re-export all public types from index.ts

web/pnpm-lock.yaml

@@ -92,6 +92,9 @@ importers:
         specifier: 3.21.4
         version: 3.21.4
     devDependencies:
+      '@types/node':
+        specifier: 26.1.0
+        version: 26.1.0
       vitest:
         specifier: 4.1.9
         version: 4.1.9(@types/[email protected])([email protected])([email protected](@types/[email protected])([email protected])([email protected]))