[1.4] Recover extensions when Kraken settings are empty

[joaoantoniocardoso]

Summary

• An empty or truncated Kraken settings file (SD-card corruption, zero-byte JSON) was treated as valid "no extensions" and the dangling-container cleaner then stopped running extension containers.
• Kraken now recovers installed extensions from extension-* containers before the cleaner runs, stamps identity labels on start for later recovery, and skips dangling cleanup while the settings list is empty.

Fixes #3574

Test plan

• Reproduced on DUT 192.168.0.177 (1.4-dev): writing {"VERSION": 2} and restarting blueos-core listed 0 extensions and left blueos.major_tom stopped, with no error in Kraken logs.
• After overlay: the same empty file recovers blueos.major_tom:2026-02-11 into settings, keeps the container running, and preserves the factory catalog. Zero-byte settings also recovers, with a WARNING on the invalid JSON.
• python core/services/kraken/recovery_check.py → ok
• journey_http --extension-lifecycle --allow-mutating on the patched DUT: vehicle bluerobotics.power-switch-calibration:v1.0.0, 168 passed / 1 skipped / 1 leftover FAIL (too-big → 400 incompatible on this board, not 507). Baseline restored to blueos.major_tom only.