Fix MCP JSON-RPC request ids

[0rdep]

Summary

• Preserve arbitrary JSON-RPC request ids for MCP HTTP clients, including strings, numbers, null, and omitted ids.
• Map external JSON-RPC ids to safe internal RPC ids so the core RPC RequestId can remain bigint-based.
• Add regression coverage for JSON-RPC serialization and the MCP HTTP server path.

Testing

• pnpm lint-fix
• pnpm test packages/effect/test/rpc/RpcSerialization.test.ts --run
• pnpm test packages/effect/test/unstable/ai/McpServer.test.ts --run
• pnpm --filter effect check
• git diff --check

pnpm check:tsgo was also run earlier and still fails on unrelated existing diagnostics in packages/effect/typetest/Effect.tst.ts about missing OtherError expectations.

Fixes #2303

[changeset-bot]

🦋 Changeset detected

Latest commit: 21ece75

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 27 packages

Name	Type
effect	Patch
@effect/opentelemetry	Patch
@effect/platform-browser	Patch
@effect/platform-bun	Patch
@effect/platform-node-shared	Patch
@effect/platform-node	Patch
@effect/vitest	Patch
@effect/ai-anthropic	Patch
@effect/ai-openai-compat	Patch
@effect/ai-openai	Patch
@effect/ai-openrouter	Patch
@effect/atom-react	Patch
@effect/atom-solid	Patch
@effect/atom-vue	Patch
@effect/sql-clickhouse	Patch
@effect/sql-d1	Patch
@effect/sql-libsql	Patch
@effect/sql-mssql	Patch
@effect/sql-mysql2	Patch
@effect/sql-pg	Patch
@effect/sql-pglite	Patch
@effect/sql-sqlite-bun	Patch
@effect/sql-sqlite-do	Patch
@effect/sql-sqlite-node	Patch
@effect/sql-sqlite-react-native	Patch
@effect/sql-sqlite-wasm	Patch
@effect/openapi-generator	Patch

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