Saved server profiles and redacted diagnostics

[mkaltner]

Scope

Add Android-native connection continuity matching the useful outcomes of current iOS:

• saved server profiles with explicit credential-retention policy;
• safe switch, rename, and delete behavior;
• server/version/capability diagnostics;
• a reviewed, redacted support bundle that can be exported or shared.

This does not require simultaneous aggregation of unrelated Arcane servers into one fleet.

Requirements

• Reuse the existing normalized server identity, token, cookie, cache, snapshot, operation, shortcut, and route isolation boundaries.
• Never expose tokens, passwords, cookies, recovery material, private resource identifiers, or notification contents.
• Define migration from the existing single configured server.
• Prove switching and deletion cannot flash or reuse another server/account's state.
• Cover process recreation, offline profiles, invalid servers, equivalent URL spellings, and active operations.
• Validate on an AVD using multiple disposable Arcane instances.

This is deferred roadmap work, not a blocker for the current Android handoff milestone.

[mkaltner]

Cross-link: #66 documents the PAR-502 rescope and preserves single-server/account isolation. Current iOS-style saved profile switching plus redacted diagnostics remain deferred here; simultaneous multi-server aggregation is explicitly separate under #62.