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/NodePrefs.h

@@ -171,8 +171,9 @@ struct NodePrefs {  // persisted to file
   // shows ✗. 0 = no auto-resend (single attempt). Default 2.
   uint8_t  dm_resend_count;
 
-  // User-saved radio presets (Settings > Radio > Preset > "Save current...").
-  // name[0] == '\0' marks an empty slot.
+  // User-saved radio presets, written by the "Save current..." entry in the
+  // shared preset picker (Settings > Radio and Tools > Repeater both populate
+  // these same slots). name[0] == '\0' marks an empty slot.
   struct UserRadioPreset {
     char name[16];
     float freq;
@@ -183,9 +184,9 @@ struct NodePrefs {  // persisted to file
   static const uint8_t USER_RADIO_PRESET_MAX = 4;
   UserRadioPreset user_radio_presets[USER_RADIO_PRESET_MAX];
 
-  // Repeater "politeness" — only consulted when client_repeat is on, via
+  // Repeater forwarding filters — only consulted when client_repeat is on, via
   // MyMesh::allowPacketForward(). Both default to off (0) so behaviour is
-  // unchanged until the user opts in (Settings > Radio).
+  // unchanged until the user opts in (Tools > Repeater).
   //  repeat_skip_adverts: 1 = don't re-flood ADVERT packets (the highest-volume
   //    flood traffic); messages/acks still relay.
   //  repeat_max_hops: drop a flood packet once it has already travelled this