Fix startup crash caused by corrupted cookie store

[arpitJ-dev]

Description (required)

Fixes #6915

CommonsCookieStorage.load() previously allowed malformed persisted cookie data to throw during application startup, leaving both the main process and ACRA process in a persistent crash loop.

This change treats an unreadable cookie store as an invalid saved session. It keeps the in-memory cookie collection empty, removes only the corrupted cookie_store preference, logs the recovery, and leaves unrelated preferences intact. Valid cookie stores and the existing plaintext-to-encrypted migration behavior are unchanged.

Unit tests cover malformed and truncated JSON, JSON null, blank values, incorrect top-level types, invalid domain values, valid empty and populated stores, invalid individual cookies, unrelated-preference preservation, and repeated loading after recovery.

Tests performed (required)

• Ran the focused CommonsCookieStorageTest and adjacent JsonKvStoreTest suites on BetaDebug: 16 tests, 0 failures.
• Tested BetaDebug on a Samsung SM-S938U running Android 16 (API 36).
• Reproduced the original main-process and ACRA crash loop with a malformed persisted cookie store.
• Installed the fixed build over the same corrupted data and confirmed successful recovery and subsequent cold launches.
• Verified recovery for a bare string, truncated JSON, JSON null, a top-level array, an invalid domain value, and whitespace-only data.
• Verified that a valid empty JSON object remains accepted and retained.

Screenshots (for UI changes only)

Not applicable; this change has no UI modifications.

[arpitJ-dev]

Hi @RitikaPahwa4444, when you have time, could you please review this PR? The fix and regression tests are included, and I also validated the recovery behavior on a physical device across multiple corrupted cookie-store inputs. Please let me know if any changes or additional testing would be helpful.

[RitikaPahwa4444]

I'll start testing 🙂

[github-actions]

✅ Generated APK variants!

• 🤖 Download prodDebugAPK
• 🤖 Download betaDebugAPK

[arpitJ-dev]

Hey @RitikaPahwa4444, just checking in, how's the testing going on this one? Happy to add more test coverage or make changes if anything came up.

Also flagging in case it's confusing: the failing check-scope check isn't related to this PR's code. The job log shows it's hitting a 410 from GitHub's own AI-inference service ("GitHub Models is temporarily unavailable as part of a scheduled retirement brownout"), so that's an outage on GitHub's end, not something in the diff. Android CI is passing fine.