Ci/v5 trigger and matrix

[mtt-ai]

Context

CI on v5 (the default branch) currently does not run — .github/workflows/ci.yml lists ["v1", "v2", "v3", "v4", "main"] in its push/pull_request triggers but omits v5. Every commit and PR to the active development branch ships without test coverage.

Changes

.github/workflows/ci.yml

• Adds v5 to both push and pull_request triggers — main fix.
• Expands matrix to 3.10/3.11/3.12/3.13 to match requires-python = ">=3.10". Python 3.13 silently skips graspologic via its existing python_version < '3.13' marker.
• Installs [all,test] instead of [mcp,pdf,watch] + sidecar pip install pytest. Tests covering transcribe (video), cluster (leiden), serve (mcp), export (svg) now have their dependencies available.
• Adds pip caching (cache: 'pip' + cache-dependency-path: pyproject.toml).
• Adds concurrency: block (cancel-in-progress: true on same ref).
• Adds explicit permissions: { contents: read } for least-privilege.
• Adds fail-fast: false so a single Python-version regression doesn't mask the others.
• Adds workflow_dispatch: for manual reruns.

pyproject.toml

Adds test = ["pytest>=7", "pytest-cov"] optional-dependencies group. Kept out of [all] deliberately — [all] is runtime extras only.

Verification

• After merge, push a trivial commit to v5 and confirm the run shows up in gh run list -R safishamsi/graphify -b v5.
• The 3.13 job should pass while skipping graspologic.
• Test count should be ≥ baseline.

Out of scope

Multi-OS matrix, coverage upload, SHA-pinning actions, pruning v1–v4 from triggers.