fix(mcp): pin mcp<2.0.0 and report fastmcp removal accurately

[erensh27]

Fixes #333.

Two fixes:

1. pyproject.toml — cap the mcp extra at mcp<2.0.0: mcp 2.0.0 (released 2026-07-28) removed mcp.server.fastmcp, so fresh skillspector[mcp] installs could resolve mcp 2.x and then fail at server init.
2. src/skillspector/mcp_server.py — on import failure, first check whether mcp itself is importable. If it is, the problem is the missing mcp.server.fastmcp submodule (mcp>=2.0.0), so the error now says so and points at pip install 'skillspector[mcp]' for a compatible pin, instead of the misleading "optional 'mcp' dependency is missing" message.

Reproduction from the issue now yields a truthful error under mcp 2.x, and pip install 'skillspector[mcp]' no longer resolves to mcp 2.x at all.

[rng1995]

Blocking: this catches every ModuleNotFoundError raised while importing FastMCP, including a missing transitive dependency inside an installed MCP 1.x package. Importing top-level mcp then succeeds and the code falsely reports that MCP 2.x removed FastMCP. Distinguish exc.name == "mcp", exc.name == "mcp.server.fastmcp", and unrelated missing modules, preserving the original error for the last case, and add tests for both incompatible-MCP and transitive-import failures.

[rng1995]

[Automated SkillSpector Review]

Requesting changes. The new error branch misdiagnoses missing transitive imports inside installed MCP 1.x as the MCP 2.x FastMCP removal, and the dependency change leaves uv.lock stale (uv lock --check fails). This branch also conflicts with main and substantially overlaps already-approved PR #339, which includes the lock and a focused regression.

[erensh27]

All review comments addressed:

• Blocking: the error branch now distinguishes exc.name == "mcp" (missing extra), exc.name == "mcp.server.fastmcp" (installed but incompatible, mcp>=2.0.0), and unrelated missing modules — the original error is preserved for the last case via raise exc.
• Tests: added coverage for all three failure modes (missing extra, incompatible install, transitive-import failure) in tests/unit/test_mcp_server.py.
• Conflict/stale lock: rebased on main. main already carries the mcp<2.0.0 pin and matching uv.lock (merged via release snapshots), so this PR no longer touches pyproject.toml/uv.lock — uv lock --check passes and the diff is now only the diagnostic fix + tests.

Verified: pytest -m "not integration and not provider" tests/ → 1939 passed; ruff check/format clean. Ready for re-review.