polish(ui): text/icon consistency pass across Tools, Settings, and menus

- RepeaterScreen: drop the redundant "Rpt " prefix on the profile fields
  (Preset/Freq/SF/BW/CR), matching Settings > Radio's own terminology --
  the screen is already dedicated to the repeater's own profile, so the
  prefix disambiguated nothing.
- Channel context menu: "Fav: yes/no" -> "Fav: ON/OFF", matching every
  other toggle in the app.
- Settings (System tab): six labels left as raw concatenated identifiers
  (AutoOff/AutoLock/TimeZone/LowBat/BattDisp/BzrVol) now read like their
  space-separated neighbours (Auto pwr/Pwr save/DM sound/GPS pwr), and
  BzrVol no longer clashes with "Buzzer" one row above it for the same
  feature. Three value-label arrays also had one mismatched-case entry
  fixed to match its siblings: Auto-off's "never" -> "OFF", Batt display's
  "icon" -> "Icon", Sound's "built-in" -> "Built-in".
- ToolsScreen: re-enabled the mini-icons next to each tool, which had
  been commented out ("don't fit visually"). Root cause: the screen's own
  drawIcon() centred against lineStep() (line height + inter-row gap)
  instead of getLineHeight() alone, 2px too generous for a near-full-
  height icon -- now delegates to the already-correct miniIconDraw() used
  elsewhere (e.g. the message-list ack checkmark). Also gave Admin and
  GPIO their own icons (padlock, 3-pin header) instead of both sharing
  System's cog.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/solo_features/message_screen/message_screen.md

@@ -137,7 +137,7 @@ In the **Rooms** list the context menu instead offers:
 | Mark all read             | Clears all unread for this channel                                    |
 | Notif: default / OFF / ON | Per-channel notification override — **LEFT/RIGHT** to cycle           |
 | Melody: global / M1 / M2  | Per-channel melody override — **LEFT/RIGHT** to cycle                 |
-| Fav: yes / no             | Add or remove this channel from favourites — **LEFT/RIGHT** to toggle |
+| Fav: ON / OFF             | Add or remove this channel from favourites — **LEFT/RIGHT** to toggle |
 | Edit                      | Opens the Add/Edit form below, pre-filled with the channel's name    |
 | Delete                    | Removes the channel immediately (no confirm prompt)                   |