fix: resolve CI failures on main — ruff lint + tomllib on Py3.10

[tirth8205]

Summary

Main CI has been red for 13 consecutive pushes since fix: resolve SQLite transaction nesting errors (#135, #181) (#205) landed. This PR fixes the actual root causes so the main branch is green again.

Root causes

Lint job (ruff check code_review_graph/) — 4 errors + 1 warning:

• communities.py:564 — E501 Line too long (104 > 100) on an INSERT INTO SQL literal
• parser.py:2435 — W291 Trailing whitespace on the Go field_identifier return
• skills.py:449 / :456 — N806 local vars _SCRIPT / _MARKER inside install_git_hook flagged as non-lowercase
• visualization.py:415 — Ruff was parsing `# noqa: E501` inside a comment explaining the per-file-ignore as a real noqa directive, which is invalid syntax

Test (3.10) job:

• tests/test_skills.py:8 — import tomllib fails on Python 3.10 (tomllib is 3.11+). Project still advertises requires-python = ">=3.10" and the CI matrix runs 3.10.

Fixes

File	Fix
code_review_graph/skills.py	Rename local vars _SCRIPT→script, _MARKER→marker in install_git_hook (they were only used inside the function — no public API change)
code_review_graph/communities.py	Wrap the long INSERT INTO communities SQL across two lines
code_review_graph/parser.py	Strip trailing whitespace
code_review_graph/visualization.py	Rephrase the explanatory comment so ruff doesn't parse the embedded noqa
tests/test_skills.py	if sys.version_info >= (3, 11): import tomllib; else: import tomli as tomllib
pyproject.toml	Add "tomli>=2.0; python_version < '3.11'" to dev extras
uv.lock	Regenerated — picks up tomli, and also fills in pytest-cov + coverage entries that were already listed in dev extras but missing from the lock on main

Test plan

Verified locally on Python 3.11:

• uv run ruff check code_review_graph/ → All checks passed!
• uv run mypy code_review_graph/ --ignore-missing-imports --no-strict-optional → Success: no issues found in 44 source files
• uv run bandit -r code_review_graph/ -c pyproject.toml → 0 High/Medium/Low issues
• uv run pytest --tb=short -q --cov=code_review_graph --cov-fail-under=65 → 661 passed, 1 skipped, 2 xpassed, coverage 72.77% (gate is 65%)
• CI matrix (3.10 / 3.11 / 3.12 / 3.13) — will run on this PR

Not in scope

• The action_required status on 20+ other open PRs is GitHub's new-contributor CI gate, not a CI failure.
• PR-specific failures (e.g. fix: bump mcp/fastmcp minimums for CVEs #144 fastmcp CVE bump) live on their own branches and should be addressed per-PR.

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