fix: support context-only resources

[pragnyanramtha]

Summary

• fix @mcp.resource classification so a function whose only parameter is Context registers as a regular resource, not a parameterless template
• store/inject context for FunctionResource reads
• keep existing Resource.read() call shape for non-function resources

Fixes #1405.

Tests

• uv run --frozen pytest tests/server/mcpserver/test_server.py -k 'resource'\n- uv run --frozen pytest tests/server/mcpserver/test_server.py::TestServerResources::test_context_only_resource_registered_as_regular_resource tests/server/mcpserver/test_server.py::TestContextInjection::test_resource_with_context\n- uv run --frozen ruff check src/mcp/server/mcpserver/resources/types.py src/mcp/server/mcpserver/server.py tests/server/mcpserver/test_server.py\n- uv run --frozen ruff format --check src/mcp/server/mcpserver/resources/types.py src/mcp/server/mcpserver/server.py tests/server/mcpserver/test_server.py\n- uv run --frozen pyright src/mcp/server/mcpserver/resources/types.py src/mcp/server/mcpserver/server.py tests/server/mcpserver/test_server.py\n- git diff --check

[maxisbey]

Thanks for the PR. Tracking this in #1666 instead. Closing as part of a general backlog cleanup following the v2 release. If this is still relevant against v2, feel free to reopen.

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