qa: plumb RADIANCE_OUTBOUND_SOCKS_ADDRESS into the Android client

[myleshorton]

Adds a debug-only path that lets a developer route every outbound network call radiance makes from the Android client through an upstream SOCKS5 (typically the local `pinger bridge`), so the bandit treats the client as a real Russia-residential user end-to-end.

Pairs with:

• radiance: qa: route all radiance egress through an upstream SOCKS5 + bandit probe driver radiance#445
• lantern-cloud: https://github.com/getlantern/lantern-cloud/pull/2649

Summary

• `lantern-core/mobile`: new gomobile-exported `SetQAEnvOverrides(socks, tz string) error` that does `os.Setenv` for `RADIANCE_OUTBOUND_SOCKS_ADDRESS` and `TZ`. Must be called before `SetupRadiance` / `StartIPCServer` to take effect (radiance reads them at init time).
• `android/.../LanternApp.kt`: override `onCreate` and call the new setter with values from Android system properties:
  • `debug.lantern.outbound_socks` → `RADIANCE_OUTBOUND_SOCKS_ADDRESS`
  • `debug.lantern.tz` → `TZ`
  • Set with `adb shell setprop debug.lantern.outbound_socks 10.0.2.2:1080`. No-op when the props are unset, so production builds aren't affected unless someone deliberately sets them on the device.
• `go.mod`: bump radiance to the qa/outbound-socks-egress branch tip. Should be re-bumped to the merged commit once radiance#445 lands.

Why two QA props

`RADIANCE_OUTBOUND_SOCKS_ADDRESS` makes radiance route through the bridge. `TZ` (`Europe/Moscow`) is needed because the API's MaxMind logic overrides the GeoIP-derived country with the timezone-derived one when they disagree (treats it as a VPN user) — see `cmd/api/maxmind.go` `LookupCountryASNState`. Without TZ also being Moscow, the API still says `country=US` even though the IP is Russia.

Verified end-to-end

Setup:
```

1. lantern-cloud bridge (separate PR)

./cmd/pinger/bridge.sh

→ SOCKS5 listening on 127.0.0.1:1080, egress: packetstream/Russia

2. emulator boot, install, configure, launch

~/Library/Android/sdk/emulator/emulator @lantern_test -no-snapshot-load -no-boot-anim
adb shell setprop debug.lantern.outbound_socks 10.0.2.2:1080
adb shell setprop debug.lantern.tz Europe/Moscow
adb install -r build/app/outputs/flutter-apk/app-debug.apk
adb shell am start -n org.getlantern.lantern/.MainActivity
```

What logcat shows:
```
LanternApp: QA env overrides applied: outbound_socks=10.0.2.2:1080 tz=Europe/Moscow
GoLog: QA: set RADIANCE_OUTBOUND_SOCKS_ADDRESS value=10.0.2.2:1080
GoLog: Skipping publicip.Detect because RADIANCE_OUTBOUND_SOCKS_ADDRESS is set
GoLog: routing all radiance HTTP through upstream SOCKS5 addr=10.0.2.2:1080
GoLog: dropping UDP-only protocols from config request kept=15 dropped=5
GoLog: every sing-box outbound will dial via this SOCKS5 addr=10.0.2.2:1080 rewritten_outbounds=7
GoLog: received config "country":"RU","ip":"85.172.81.50" # Volgograd, AS12389 Rostelecom
```

Browsing `https://api.ipify.org\` in the emulator's Chrome shows the Lantern outbound's exit IP (Stockholm/Singapore depending on which the bandit's auto-pick converges on), not the Mac's home IP.

Test plan

• Default (no QA props): Lantern boots normally, no `QA env` log lines, kindling uses its stacked transports as usual. Production behavior preserved.
• With `debug.lantern.outbound_socks` set + bridge running: API sees `country=RU` and a Russia residential IP; `auto` URLTest converges on a TCP outbound from the Russia-tier set; browsing through the tunnel egresses from the entry-server location.
• With invalid system prop value (e.g. unreachable host): Lantern logs the QA hook firing but radiance's first `/v1/config-new` retries until cancelled; no crash, no production-data leakage.
• `adb shell setprop debug.lantern.outbound_socks ""` then re-launch: app reverts to default kindling/no-detour behavior.

Known caveats

• The bridge SOCKS5 listener is TCP-only (no UDP ASSOCIATE), which is why the radiance PR also drops UDP-only protocols from the request. Hysteria-class protocols don't work in Russia anyway, so this is fine in scope. If we ever want UDP coverage, we'll need to add UDP ASSOCIATE to the bridge.
• The first 10s after launch may use stale cached config from the previous boot (which can include UDP outbounds and emit transient `code=7` errors). Once the fresh `/v1/config-new` response arrives, only TCP outbounds are in rotation. Cleaner solution would be wiping `/.lantern/data/config.json` when the QA env is set; deferred.

🤖 Generated with Claude Code

[jigar-f]

@myleshorton Lets make sure this is across android version? This can easily cause a crash. Did you run on an older version?