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>

FEATURES.md

@@ -441,7 +441,7 @@ Sequencing: hardware duty-cycle RX and APC are both done and in field test on
 `feat/power-saving`; see the status block at the top of this entry for what's
 left (PPK2 current measurement, multi-hop APC gating).
 
-### ✅ Companion repeater + politeness knobs + diagnostics
+### ✅ Companion repeater + forwarding filters + diagnostics
 
 On-device repeater for the Solo companion, scoped to the SX1262 boards (Wio
 Tracker L1 OLED/e-ink, GAT562 30S). All on `feature/companion-repeater-presets`.
@@ -478,7 +478,7 @@ Tracker L1 OLED/e-ink, GAT562 30S). All on `feature/companion-repeater-presets`.
   outside what's legal for wherever the companion's own network already is.
   `LORA_FREQ/BW/SF/CR` fallback `#define`s moved from `MyMesh.h` to
   `NodePrefs.h` so `DataStore.cpp`'s migration code can see them too.
-- **Politeness knobs** (all opt-in, default off, flood-only — a direct route's
+- **Forwarding filters** (all opt-in, default off, flood-only — a direct route's
   named next hop is never dropped). Shown only while the repeater is on:
   - **Skip advert** — don't re-flood adverts (highest-volume flood).
   - **Max hops** — drop a flood past N hops.