docs+site: sync copy to current reality, dark theme by default

[Paritsingla7]

Summary

Documentation/site coherence pass — brought public-facing copy in line with what the tool actually does now (v0.4.0: convert, check, --fix, diff-impact), and made dark the site's actual default theme rather than conditional on the visitor's OS preference.

• README: test badge said 170, actual count is 219 — fixed.
• pyproject.toml / packaging/PKGBUILD: description reordered to lead with validate/auto-fix; convert is the entry point now, not the whole story.
• site/index.html:
  • Added §4 (The fixer) and §5 (Stay working through the next update) — the page previously had zero mention of --fix or diff-impact anywhere.
  • Corrected a factually wrong claim in §3: it said { mouse = true } "doesn't exist in the real schema" and that drag is "the real replacement." Confirmed via Hyprland's own source (LuaKeybind.cpp) that mouse is a real, separately-implemented flag — just missing from Hyprland's own stub generator, not a wiki mistake. Reworded to reflect that accurately.
  • Dark is now the page's unconditional default theme (previously only shown if the visitor's OS/browser already preferred dark).

docs/COMPARISON.md and CONTRIBUTING.md were checked too and found still accurate — no changes needed there (re-ran docs/measure_comparison.py live; the "51 dispatchers" figure still reproduces exactly).

Test plan

• pytest tests/ — 216 passed (3 pre-existing/environmental entry-point failures unrelated, deselected)
• Verified the dark theme renders correctly and unconditionally via the browser preview
• Verified the new site sections render in the correct order with the rest of the page