fix: bug bash — FlexRadio crashes, TCP hang, dead audio pad, charset

[patrickrb]

Summary

Four independent latent bugs surfaced during a bug-bash sweep across FlexRadio, the Flex TCP client, the FT8 TX path, and the QRZ/Cloudlog HTTP client. None are regressions from a recent change.

• FlexRadio.getHeadAndContent (`FlexRadio.java:1170`) — guarded `temp[1]` with `line.length() > 1`, which is unrelated to the split-array length. A no-delimiter response crashes the CAT parser thread with `ArrayIndexOutOfBoundsException`. Now checks `temp.length >= 2`.
• FlexRadio command dispatch (`FlexRadio.java:1077`) — `FlexCommand.values()[seq_number % 1000]` assumed the enum had ≥1000 entries; an out-of-range sequence number crashed with AIOOBE. Now bounds-checked, unknown commands are logged and skipped.
• RadioTcpClient TCP connect (`RadioTcpClient.java:99`) — `new Socket(addr, port)` used the OS default connect timeout (~75 s on Linux), so an unreachable Flex hangs the connect thread that long with no UI feedback. Replaced with the two-step `connect(InetSocketAddress, 5000)` + `setSoTimeout(15000)` pattern.
• FT8TransmitSignal.float2Short (`FT8TransmitSignal.java:341`) — allocated `short[buffer.length + 8]` "for QP-7C RP2040 audio detection compatibility", but the 16-bit `AudioTrack.write` uses `playLength = buffer.length - skipSamples` and never includes those 8 trailing samples. The 32-bit float path doesn't add the pad at all. Dropped the dead allocation and the misleading comment.
• ThirdPartyService.sendGetRequest (`ThirdPartyService.java:553`) — `InputStreamReader` without an explicit charset reads QRZ/Cloudlog responses with the platform default. The sibling reader near line 443 already uses UTF-8; this one-line divergence corrupts non-ASCII responses on non-UTF-8 default locales.

Test plan

• Builds clean on `fix/bug-bash` (verified during full `gradlew installDebug` from the parent branch with the same edits)
• FlexRadio bounds fixes — synthetic test feeding a no-delimiter line and a high-`seq` response to the parser (no Flex on hand to exercise live)
• TCP timeout — point Flex IP at `192.0.2.1` (TEST-NET-1), confirm connect attempt fails in ~5 s with visible error
• `float2Short` change is a no-op for non-QP-7C TX — confirm TX'd FT8 still decodes on a second receiver
• UTF-8 charset on QRZ reader — code-review parity with line-443 reader; full validation needs a non-UTF-8 locale device

Related

Companion fixes that touch POTA-only files (DatabaseOpr migration repair, POTA self-spot frequency, POTA ADIF exporter UTF-8 length) were pushed to PR #96 since they only apply where the POTA branch's files exist.

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