Wi-Fi Tools: scan logging to CSV, plus sort and filter

- lib/wifi (host-tested): scan_log (CSV field quoting, header/row, a
  once-per-interval throttle) and network_list_view (sort by signal /
  channel / name, filter open-only / hide-hidden / strong-only)
- ScanEntry moved to lib/wifi so both are testable on the PC
- Wi-Fi Tools networks view: s sort, o/h/w filters, l toggles logging
  to /wifi/scans/<date>.csv (header + one row per AP per logged scan,
  throttled 30 s, needs the clock for timestamps); foreground-only
- Wi-Fi scan logs replace probe-request logs as a clean-up category
- Serial: cat <path>, and key <char> injects a character

Verified on the device: CSV written with header, timestamps, BSSID,
channel, RSSI, security and SSID; hidden networks marked.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

lib/storage_model/src/cleanup_plan.h

@@ -18,7 +18,7 @@ struct CleanupCategory {
 };
 inline const CleanupCategory kCleanupCategories[] = {
     {"IRC logs", "/irc"},
-    {"Probe-request logs", "/wifi/probes"},
+    {"Wi-Fi scan logs", "/wifi/scans"},
     {"Wi-Fi captures", "/captures/wifi"},
 };