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/ui-new/DiagnosticsScreen.h

@@ -9,13 +9,14 @@
 
 extern MyMesh the_mesh;
 
-// Single-screen device diagnostics: packet counts by category (RX/TX), radio
-// totals, uptime, heap and stack headroom. Built from Dispatcher's per-type
-// counters (Mesh.h/Dispatcher.cpp) — grouped into a handful of categories
-// rather than all 16 raw PAYLOAD_TYPE_* values, so it stays readable on a
-// 128x64 OLED without needing the full type list. Falls back to scrolling
-// (same drawList-style indicator as every other screen) on screens too small
-// to show every row at once.
+// Single-screen device diagnostics: uptime, packet counts by category (RX/TX),
+// forwarded-packet count, heap and stack headroom, radio signal (noise floor,
+// RSSI/SNR), packet-pool/outbound-queue depth, and radio error flags. The packet
+// counts are built from Dispatcher's per-type counters (Mesh.h/Dispatcher.cpp) —
+// grouped into a handful of categories rather than all 16 raw PAYLOAD_TYPE_*
+// values, so they stay readable on a 128x64 OLED without the full type list.
+// Falls back to scrolling (same drawList-style indicator as every other screen)
+// on screens too small to show every row at once. Hold Enter resets the counters.
 class DiagnosticsScreen : public UIScreen {
   UITask* _task;
   int _scroll = 0;