Expose insurance fund claim mechanism

[0xdevcollins]

Problem

The fee-on-top model collects insurance fees on every pledge (default 30% of fee), but there is no function to claim or use insurance funds. The insurance pool becomes dead money.

Current Behavior

• Pledge fee split: treasury (70%) + insurance (30%)
• Insurance funds accumulate in CoreEscrow
• No claim_insurance() or similar function exists
• If campaigns fail or disputes arise, backers are refunded from the main pool only

Expected Behavior

1. claim_insurance(campaign_id, claimant, amount, reason) — Admin-only, allows drawing from insurance pool for:
   • Disputed campaigns where backer is owed compensation
   • Partial recovery for failed campaigns
   • Emergency situations
2. get_insurance_balance() — Query available insurance funds
3. Insurance usage should be auditable (events emitted)

Acceptance Criteria

• Admin can claim insurance funds with documented reason
• Insurance balance queryable
• Events emitted for all insurance operations
• Tests cover claim, insufficient balance, and unauthorized access

Priority

Low — Not blocking core flow, but collected funds should be usable.

Labels

crowdfunding, smart-contract, enhancement

[0xdevcollins]

Already Implemented in CoreEscrow

After investigation, the CoreEscrow contract already has full insurance fund management:

Existing Functions

• claim_insurance(claimant, amount, asset) — Admin-only, transfers insurance funds to a claimant. Emits InsuranceClaimed event with claimant and amount. (core_escrow/src/contract.rs:624-658)
• get_insurance_balance() — Returns current insurance pool balance. (core_escrow/src/contract.rs:105-111)
• contribute_insurance(amount) — Public function to add funds to insurance pool. (core_escrow/src/contract.rs:596-622)

Tracking

The InsuranceFund struct tracks:

• balance — current available funds
• total_contributions — lifetime insurance collected
• total_paid_out — lifetime insurance claimed

Events

• InsuranceClaimed { claimant, amount } — emitted on every claim
• InsuranceContributed { amount } — emitted on every contribution

Test Coverage

Existing test at core_escrow/src/tests/mod.rs:345 covers the claim flow.

No contract changes needed — this can be closed as already implemented. The admin calls claim_insurance directly on the CoreEscrow contract address.