docs: factual-drift pass + i2c option docs (#47, #48)

Fix documentation drift (each claim verified against code): theme count
21→24; waybar whole-swap lists (waybar.css=5 incl. neon-glass vs
waybar.jsonc parity=4 + boreal); idle "suspend 30"→"15 min battery-only";
Tailscale sudo→operator; hosts/live.nix "No installer yet" header; link
docs/MIGRATION.md + fix its placeholder URL; README layout tree
(+doctor/control-center/battery-notify); OVERRIDES swappy→satty; document
always-on home pieces. String fixes: keybind cheatsheet
nmtui→networkmanager_dmenu; complete nomarchy-menu usage string
(+doctor/firmware/controlcenter/rollback). Add README rows for
nomarchy.hardware.i2c.* (#48) — closes checks.option-docs.

Implemented by a worktree agent; diff reviewed and cherry-picked.
Verified V0 (flake check) + checks.option-docs green + V1 (HM build).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

templates/downstream/README.md

@@ -25,7 +25,7 @@ keyboard, detected hardware, password hash, …). Keep commented opt-ins and
 Day-to-day:
 
 ```sh
-nomarchy-theme-sync list             # 21 shipped presets
+nomarchy-theme-sync list             # 24 shipped presets
 nomarchy-theme-sync apply gruvbox    # writes state + home-manager switch
 nomarchy-theme-sync bg next          # cycle wallpapers (instant, no rebuild)
 ```