[Security/Privacy] Timing-correlation mitigation between post submission and on-chain anchor

Problem

If confessions are anchored to Stellar shortly after posting, an attacker correlating on-chain anchor timestamps with off-chain activity (IP logs, session timing) could de-anonymize posters.

Scope

• Audit the current anchoring flow for timing characteristics.
• Implement batching, delay, or timestamp jitter before anchoring.
• Consider aggregate/batch anchoring of multiple confessions per on-chain transaction.

Why it's hard

Requires balancing anchoring integrity guarantees against privacy, and reasoning about timing side-channels at the protocol level.

Acceptance criteria

• Anchoring no longer has a tight, predictable time correlation to submission time.
• Documented threat model showing the mitigation's effectiveness and limits.