feat: WiFi Locate mode, mobile nav groups, v2.24.0

Add WiFi Locate mode for locating access points by BSSID with real-time
signal meter, distance estimation, RSSI history chart, and audio
proximity tones. Includes hand-off from WiFi detail drawer, environment
presets (Free Space/Outdoor/Indoor), and signal-lost detection.

Also includes:
- Mobile navigation reorganized into labeled groups (SIG/TRK/SPC/WIFI/INTEL/SYS)
- flask-limiter made optional with graceful degradation
- Fix radiosonde setup missing semver Python dependency
- Documentation updates (FEATURES, USAGE, UI_GUIDE, GitHub Pages site)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

static/js/core/cheat-sheets.js

@@ -8,6 +8,7 @@ const CheatSheets = (function () {
         wifi:        { title: 'WiFi Scanner',            icon: '📡', hardware: 'WiFi adapter (monitor mode)',              description: 'Scans WiFi networks and clients via airodump-ng or nmcli.',                 whatToExpect: 'SSIDs, BSSIDs, channel, signal strength, encryption type.',    tips: ['Run airmon-ng check kill before monitoring', 'Proximity radar shows signal strength', 'TSCM baseline detects rogue APs'] },
         bluetooth:   { title: 'Bluetooth Scanner',       icon: '🔵', hardware: 'Built-in or USB Bluetooth adapter',        description: 'Scans BLE and classic Bluetooth devices. Identifies trackers.',              whatToExpect: 'Device names, MACs, RSSI, manufacturer, tracker type.',        tips: ['Proximity radar shows device distance', 'Known tracker DB has 47K+ fingerprints', 'Use BT Locate to physically find a tracker'] },
         bt_locate:   { title: 'BT Locate (SAR)',         icon: '🎯', hardware: 'Bluetooth adapter + optional GPS',         description: 'SAR Bluetooth locator. Tracks RSSI over time to triangulate position.', whatToExpect: 'RSSI chart, proximity band (IMMEDIATE/NEAR/FAR), GPS trail.',   tips: ['Handoff from Bluetooth mode to lock onto a device', 'Indoor n=3.0 gives better distance estimates', 'Follow the heat trail toward stronger signal'] },
+        wifi_locate: { title: 'WiFi Locate',              icon: '📶', hardware: 'WiFi adapter (monitor mode)',              description: 'Locate a WiFi AP by BSSID with real-time signal strength tracking.', whatToExpect: 'Big dBm meter, signal bar, RSSI chart, distance estimate, proximity beeps.', tips: ['Handoff from WiFi mode — click Locate on any network', 'Deep scan required for continuous RSSI updates', 'Indoor n=3.5 gives better distance estimates indoors', 'Enable audio for proximity tones that speed up as you get closer'] },
         meshtastic:  { title: 'Meshtastic',              icon: '🕸️', hardware: 'Meshtastic LoRa node (USB)',               description: 'Monitors Meshtastic LoRa mesh network messages and positions.',             whatToExpect: 'Text messages, node map, telemetry.',                          tips: ['Default channel must match your mesh', 'Long-Fast has best range', 'GPS nodes appear on map automatically'] },
         adsb:        { title: 'ADS-B Aircraft',          icon: '✈️', hardware: 'RTL-SDR + 1090MHz antenna',               description: 'Tracks aircraft via ADS-B Mode S transponders using dump1090.',             whatToExpect: 'Flight numbers, positions, altitude, speed, squawk codes.',     tips: ['1090MHz — use a dedicated antenna', 'Emergency squawks: 7500 hijack, 7600 radio fail, 7700 emergency', 'Full Dashboard shows map view'] },
         ais:         { title: 'AIS Vessels',             icon: '🚢', hardware: 'RTL-SDR + VHF antenna (162 MHz)',          description: 'Tracks marine vessels via AIS using AIS-catcher.',                         whatToExpect: 'MMSI, vessel names, positions, speed, heading, cargo type.',    tips: ['VHF antenna centered at 162MHz works best', 'DSC distress alerts appear in red', 'Coastline range ~40 nautical miles'] },