Replace hardcoded NUM_ANCHORS with dynamic discovery table.
Tag probes IDs 0..7 via standard DS-TWR POLL frames at startup
and after every DISC_RESCAN_MS (10 s); anchors that respond are
added to the active table, stale ones removed after
ANCHOR_MISS_LIMIT misses or ANCHOR_TIMEOUT_MS silence.
Key changes
-----------
- AnchorEntry table (8 slots): present/active flags, range_mm,
rssi, last_ok_ms, miss_count
- DISC_SCAN → DISC_RANGE state machine
- range_and_update(): ranges, updates table, emits +DISC:FOUND /
+DISC:LOST on serial and MSG_DISC (0x40) on ESP-NOW
- disc_scan_step(): advances cursor one probe per ranging slot,
skips already-active IDs
- New OLED screens: ANCHOR SCAN progress bar, NO ANCHOR rescan
countdown, active anchor count badge on normal screen
- platformio.ini: switch to MaUWB_DW3000 lib, remove NUM_ANCHORS
build flag (discovery is now dynamic)
- No anchor firmware changes required
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
