Refresh docs for alpha06 cross-profile support

[Stem0794]

Summary

• document Android 11+ per-app cross-profile eligibility controls in the README and website
• add a README FAQ for apps such as microG that need Android's cross-profile connection flow
• record the confirmed microG flow on Xiaomi Lisa / LineageOS 23.2 as feature-specific evidence, not a full compatibility pass

Verification

• current source version is 0.2.0-alpha06 (versionCode=8)
• GitHub latest release is v0.2.0-alpha06
• F-Droid currently lists 0.2.0-alpha06 (8) as the suggested version
• issue Can't connect MicroG to work profile #8 reporter confirmed the microG flow works after enabling Harbor's alpha06 cross-profile control
• unresolved HyperOS issue New user questions #19 is intentionally not presented as verified compatibility data

Docs/site only; no application code or policy behavior changed.