docs(repeater): rename "politeness" -> "forwarding filters", fix stale refs

Rename the repeater filter knobs from "politeness" to "forwarding
filters" across code comments, FEATURES.md and the docs, and correct
references that hadn't followed the controls when they moved from
Settings › Radio to the dedicated Tools › Repeater screen.

Comment/doc accuracy fixes:
- NodePrefs: user_radio_presets are now written by both Settings and
  Repeater (shared picker), not Settings only.
- DiagnosticsScreen: class header listed only some rows; spell out the
  full set (forwarded, signal, pool/queue, error flags, reset gesture).
- RepeaterScreen header no longer claims to show live forwarding stats
  (they live on Diagnostics).
- tools_screen.md: drop the stale paragraph claiming the Repeater screen
  shows live stats at the bottom — it is config-only.

Comments/docs only; no behaviour change.

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

examples/companion_radio/DataStore.cpp

@@ -336,7 +336,7 @@ void DataStore::loadPrefsInt(const char *filename, NodePrefs& _prefs, double& no
   rd(&_prefs.bot_quiet_end,       sizeof(_prefs.bot_quiet_end));
   rd(_prefs.bot_trigger_ch,       sizeof(_prefs.bot_trigger_ch));
   rd(_prefs.user_radio_presets,   sizeof(_prefs.user_radio_presets));
-  // → 0xC0DE000E: repeater politeness knobs. On a pre-E file the bytes here are
+  // → 0xC0DE000E: repeater forwarding-filter knobs. On a pre-E file the bytes here are
   // that file's own sentinel tail, so clamp every out-of-range value back to its
   // "off" default (same stray-byte handling as the fields below).
   rd(&_prefs.repeat_skip_adverts, sizeof(_prefs.repeat_skip_adverts));