docs(site): make docs-site the knowledge base — status tracker + setup guides

Per the new docs workflow (docs-site = KB layer; repo docs/ keeps design notes):
- Add a canonical Status & Progress tracker (status.md): milestones, per-box live
  state, and a dated progress log — the go-forward place to track progress.
- Add setup guides: GNOME/Mutter host (gnome-box — Secure Boot MOK enroll, the
  libnvidia-gl EGL fix, autologin, screen-lock disable, appliance unit), headless
  KDE box, and Bazzite host (ujust input group, gamescope session, gotchas).
- Roadmap is now canonical in docs-site (synced the skew-handshake section 12
  update); removed the repo docs/roadmap.md copy and repointed README to docs-site.
- Nav (meta.json) + landing cards updated; site builds (bun run build).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs-site/content/docs/meta.json

@@ -3,11 +3,15 @@
   "pages": [
     "index",
     "overview",
+    "status",
     "implementation-plan",
     "roadmap",
     "m2-plan",
     "---Setup---",
     "linux-setup",
+    "headless-box",
+    "gnome-box",
+    "bazzite",
     "windows-host",
     "dualsense-haptics"
   ]