A changelog that names what changed, not the git log

[capazme]

The problem

GET /version handed the UI a raw git log -10. Around a release the first
entry is chore: bump version to X, followed by reverts and one line per
development step. Nothing in it told a reader what changed for them.

What this does

Reads the first-parent log, so each entry is a branch that landed rather
than a step inside one — and in this repo those merge subjects are already
written as summaries of the whole branch.

• A revert cancels the work it undid. On main today that removes the entire
  case-law body of work: a filter by commit type would have kept ~25
  feat(case-law) commits and advertised a feature the product no longer has.
• Housekeeping types (build/chore/ci/docs/refactor/style/test) and toolchain
  scopes are dropped; the list is capped at 20.
• The window is the current version, found from the commits that touch
  version.txt, so "Novità in vX" names the content of X.

The rules live in visualex_api/tools/changelog.py, pure and tested without a
repository. The technical panel in Impostazioni is unchanged — message is
still the raw subject.

Before / after, on main as it stands

chore: bump version to 1.3.0                                  →  CORREZIONE  keep two findings the case-law revert would have thrown away
Revert "merge: live case law from four courts…"               →              accessible names for the sidebar controls
Revert "merge: the case-law panel on the reading surface"     →              malformed bodies answer 400 instead of 500
fix(dateUtils): reject an out-of-range month in formatDate…   →  NOVITÀ      show what the system already recognises, alongside your own

Carried along

The component's primary-<number> classes generated nothing:
frontend/tailwind.config.js is a v3-style config and Tailwind v4 never loads
it (no @config directive). Fixed in the file this PR touches, using blue-*
— the same palette the config meant. 563 occurrences remain across 59 other
files, including the focus-visible:ring-primary-500 that CLAUDE.md
prescribes for accessibility. Worth its own change.

Verification

• pytest tests/ — 400 passed, 1 deselected (14 new, written before the code)
• cd frontend && npm run test — 192 passed (5 new); npm run build and
  npm run lint clean
• cd backend && npm test — 35 passed (untouched by this change)
• GET /version smoke-tested against the real repo: 200, 20 entries
• Visual pass in both themes, by mounting the component against the built CSS

🤖 Generated with Claude Code