feat: complete missing v1 protocol methods

[frostming]

Summary

The v1 schema already defines session/delete and several other methods that the SDK could neither send nor dispatch. Add typed interfaces, connection methods, routes, and public model exports for session deletion, logout, provider management, bidirectional MCP, NES, and document notifications.

session/delete and logout work without opting into unstable protocol support, matching the pinned schema-v1.23.0 stable method table. Provider, MCP, NES, and document methods remain behind use_unstable_protocol=True. MCP requests preserve arbitrary JSON results, including null, and use a separate Python method for notifications on the same wire method.

Also fix signature generation for inline Literal annotations used by the new methods. No schema regeneration or schema version change is included.

Related issues

None linked.

Testing

• NO_PROXY=localhost,127.0.0.1 no_proxy=localhost,127.0.0.1 make test: 306 passed, 1 skipped. Loopback proxy bypass avoids the local SOCKS proxy interfering with WebSocket tests; the opt-in Gemini smoke test is skipped.
• make check: passed lockfile, pre-commit, type, and dependency checks.
• New tests cover request/notification roundtrips, bidirectional MCP and null results, legacy deletion calls, missing handlers, invalid deletion parameters, stable methods without the unstable flag, method-table coverage, and inline Literal signature generation.

Docs & screenshots

Update the quickstart with the method mapping, stable versus unstable behavior, session deletion example, and MCP request/notification usage.

Checklist

• Conventional Commit title (e.g. feat:, fix:).
• Tests cover the change or are not required (explain above).
• Docs/examples updated when behaviour is user-facing.
• Schema regenerations (make gen-all) are called out if applicable.