fix(mcpserver): return resource not found code

[go165]

Fixes #1579.

Summary:

• return JSON-RPC error code -32002 for MCPServer resources/read unknown URI
• preserve direct MCPServer.read_resource() behavior as ResourceError while translating the protocol response at the request-handler boundary
• keep resource handler failures on the existing generic ResourceError path
• remove the interaction-suite divergence note for this requirement

Validation:

• PYTHONPATH=src /home/ubuntu/modelcontextprotocol-python-sdk/.venv/bin/python -m pytest tests/server/mcpserver/test_server.py::TestServerResources::test_read_unknown_resource tests/issues/test_141_resource_templates.py::test_resource_template_edge_cases tests/interaction/mcpserver/test_resources.py -q: 20 passed
• /home/ubuntu/modelcontextprotocol-python-sdk/.venv/bin/python -m ruff check src/mcp/server/mcpserver/server.py src/mcp/server/mcpserver/exceptions.py tests/interaction/mcpserver/test_resources.py tests/interaction/_requirements.py tests/server/mcpserver/test_server.py tests/issues/test_141_resource_templates.py: passed
• /home/ubuntu/modelcontextprotocol-python-sdk/.venv/bin/python -m pyright --pythonpath /home/ubuntu/modelcontextprotocol-python-sdk/.venv/bin/python src/mcp/server/mcpserver/server.py src/mcp/server/mcpserver/exceptions.py: 0 errors
• git diff --check: passed

Note: uv is not available on this machine, so I reused the existing local python-sdk virtualenv and set PYTHONPATH=src to test this worktree.

[go165]

Validation update for latest head 44d272e: GitHub CI is now green across pre-commit, readme snippets, the Python test matrix, client/server conformance, zizmor, and all-green.

Local checks also passed:

• pytest tests/interaction/mcpserver/test_resources.py tests/issues/test_141_resource_templates.py tests/server/mcpserver/resources/test_resource_manager.py tests/server/mcpserver/servers/test_file_server.py -q (36 passed)
• ruff check src/mcp/server/mcpserver/server.py tests/interaction/mcpserver/test_resources.py tests/interaction/_requirements.py tests/issues/test_141_resource_templates.py
• pyright src/mcp/server/mcpserver/server.py (0 errors)
• git diff --check