Add secondary WiFi adapter (wlan1) support

[PanGalactic]

Summary

Add dashboard support for managing a secondary WiFi adapter (wlan1) on boards with Broadcom chips that support virtual interfaces. This enables simultaneous connections — e.g. wlan0 for home WiFi and wlan1 for a robot's point-to-point hotspot.

• 5 new API endpoints for wlan1: status, scan, connect, disconnect, create interface
• New dashboard section mirroring the primary WiFi UI
• Fix: primary status now correctly filters to wlan0 only (previously, wlan1 connections could mask wlan0 state)
• Add IP address display to both primary and secondary status

Changes to existing code

Only 3 lines of existing code were modified (all in wifi_config.py):

1. get_current_wifi_mode() — mode detection

# Before:
elif any(c.device != "--" for c in conn):
# After:
elif any(c.device == "wlan0" for c in conn):

Fixes latent bug where wlan1 connection could prevent wlan0 hotspot creation.

2. get_wifi_status() — known_networks filter

# Before:
known_networks = [c.name for c in connections if c.name != "Hotspot"]
# After:
known_networks = [c.name for c in connections if c.name != "Hotspot" and not c.name.endswith("-wlan1")]

Hides secondary adapter connection profiles (suffixed -wlan1) from primary UI.

3. get_wifi_status() — connected_network filter

# Before:
connected_network = next((c.name for c in connections if c.device != "--"), None)
# After:
connected_network = next((c.name for c in connections if c.device == "wlan0"), None)

Primary status now correctly reports only wlan0 connection.

New API endpoints

Method	Path	Description
GET	/wifi/status2	Secondary adapter status (exists, connected, ssid, ip, known_networks, busy)
POST	/wifi/scan2	Scan for networks visible from wlan1
POST	/wifi/connect2	Connect wlan1 to a network
POST	/wifi/disconnect2	Disconnect wlan1
POST	/wifi/create_interface	Create wlan1 virtual interface via iw if missing

Design notes

• Why raw subprocess for wlan1: The nmcli Python library doesn't support ifname targeting for virtual interfaces. Primary adapter continues using the nmcli library.
• Connection naming: Secondary connections are named {ssid}-wlan1 to keep NM profiles distinct per interface.
• Interface creation: Uses iw dev wlan0 interface add wlan1 type managed via sudo. Requires passwordless sudo (standard on Reachy — daemon runs as pollen with sudo).
• Subprocess patterns: All subprocess calls use timeout=NMCLI_COMMAND_TIMEOUT and exception handling matching volume.py patterns.

Backward compatibility

• GET /wifi/status — same fields + new ip_address (additive, non-breaking)
• All existing endpoints completely untouched
• All new endpoints use distinct paths — no collisions
• Hotspot fallback logic fully preserved

Test plan

• Primary WiFi section works as before (status, scan, connect)
• Secondary WiFi section shows wlan1 status correctly
• Can disconnect wlan1 and reconnect
• Hotspot fallback still works when wlan0 disconnects
• Daemon restarts cleanly with new code
• Both endpoints return correct JSON
• Test on board without wlan1 — should show "WiFi adapter not available" with Create Interface button

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