[058] Implement secure data deletion

[konard]

Parent epic: #1

Phase: Security and Licenses
Priority: 58

Scope

Add secure deletion flows for local account data, cached media, agent memory, and wallet-related local state.

Implementation Steps

• Define deletion scopes and platform-specific storage locations.
• Add confirmation, progress, and recovery-window behavior where appropriate.
• Document limitations of secure deletion on each platform filesystem.

Acceptance Criteria

• Users can request deletion for account, cache, agent, and wallet local data scopes.
• Deletion confirmations clearly describe irreversible effects.
• Platform limitations receive human security review.

Automation

Generated from #1 using scripts/decompose-epic.mjs.