Fix audio encoder channel handling and release analysis findings

[TobiasRoeddiger]

The encoder could use an uninitialized frame length when input/output channel locations did not overlap. Selecting only the right channel from stereo input also read the left channel, and mono-to-mono input was rejected. Validate overlap, track the input channel independently, and normalize mono consistently. Seven regression tests exercise the production wrapper with a stub LC3 codec.

Also clear the other CodeChecker findings, make the intentional pressure-timing conversion explicit, and align the beta publisher with main to remove the release PR’s workflow conflict. The audio-buffer fatal policy is preserved.

Validation:

• Normal and FOTA firmware builds pass locally; GitHub firmware build passes.
• All five unit-test suites pass, including seven encoder tests. A host harness reproduces four failures before the patch and passes all seven cases afterward with address/undefined-behavior sanitizers.
• CodeChecker: zero non-style findings (previously eight).
• Publisher fixtures pass for modern ZIP, legacy ELF, missing artifacts, and version names; a trial merge with current main has no conflicts.
• The compiler check passes with the existing legacy USB API deprecation remaining. No hardware flash or listening test was performed for this PR.

Targets the 2.3.0 release branch, currently named 2.2.10 (#295).

[github-actions]

✅ Unit tests passed

5 passed, 0 failed/error, 0 skipped — view workflow run

Test scenario	Platform	Result
openearable.unit.sensor_component	native_sim/native/64	✅ passed
openearable.unit.sensor_transport	native_sim/native/64	✅ passed
openearable.unit.ring_buffer	native_sim/native/64	✅ passed
openearable.unit.audio_encoder	native_sim/native/64	✅ passed
openearable.unit.audio_startup	native_sim/native/64	✅ passed

Download the unit-test-results artifact for full Twister reports and logs.

[github-actions]

Compiler warnings

The extended-warning build completed successfully.

Application compiler warnings

Show warnings

unicast_server/main.cpp:78:33: warning: 'int usb_enable(usb_dc_status_callback)' is deprecated [-Wdeprecated-declarations]

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[github-actions]

CodeChecker static analysis

✅ No non-style issues found.

[github-actions]

Build output available:
openearable_v2_firmware.zip
openearable_v2_fota.zip