v1.21.0 — fusaops fleet --format html

v1.21.0 — `fusaops fleet --format html`

New feature

• `fleet.Render(w, fr, "html")` — new format producing a self-contained HTML page with:
  • Overall PASS/WARN/FAIL status badge
  • Per-repo status table (name, status badge, errors, warnings, infos, total) with colour-coded severity cells
  • Summary footer row
  • No external CSS or JS
    (REQ-FO-FLT005)
• `fusaops fleet --format html [--output fleet.html]` — generate a fleet HTML report from the CLI. (REQ-FO-FLT005)
• `fleet.Render` error message updated: "want text or json" → "want text, json, or html".

Safety

• Requirements registry at 244 requirements (added REQ-FO-FLT005)
• 4 new tests; 244/244 requirements traced+tested; combined coverage 81.2%