fix: restore MCP server startup under pydantic 2.11 / fastmcp 2.12

The server crashed on startup with two cascading pydantic errors while
fastmcp built output schemas from typed tool return annotations:

1. typing.TypedDict is rejected by pydantic on Python < 3.12 — import
   TypedDict/NotRequired/Required from typing_extensions instead
   (tool_responses.py and vector_backend/sync.py).
2. The hand-rolled recursive JsonValue alias was "not fully defined":
   fastmcp builds the output TypeAdapter in its own module namespace, so
   the "JsonValue" string forward-ref could not be resolved. Use
   pydantic's built-in recursive JsonValue and drop the now-unneeded
   `from __future__ import annotations`.

Loose version pins (pydantic>=2.7, fastmcp>=2.1) let newer releases pull
in the stricter behavior; the startup test mocks FastMCP, so the real
schema-building path was never exercised in CI.

Verified: server completes the MCP initialize handshake, tools/list
returns all 18 tools with schemas, and `claude mcp list` reports
Connected.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: SamuelBrudner

src/labarchives_mcp/schemas/tool_responses.py

@@ -1,11 +1,11 @@
 """Typed response contracts for LabArchives MCP tools."""
 
-from __future__ import annotations
+from typing import Literal, TypeAlias
 
-from typing import Literal, NotRequired, Required, TypeAlias, TypedDict
+from pydantic import JsonValue
+from typing_extensions import NotRequired, Required, TypedDict
 
 JsonScalar: TypeAlias = str | int | float | bool | None
-JsonValue: TypeAlias = JsonScalar | list["JsonValue"] | dict[str, "JsonValue"]
 JsonObject: TypeAlias = dict[str, JsonValue]
 
 

src/vector_backend/sync.py

@@ -9,7 +9,8 @@
 
 from collections.abc import Mapping, Sequence
 from datetime import UTC, datetime, timedelta
-from typing import TypedDict
+
+from typing_extensions import TypedDict
 
 from vector_backend.build_state import should_rebuild
 from vector_backend.models import BuildRecord