docs: add bounty economics explainer page

[0takuc0mrade]

Summary

Document the game-theoretic rationale behind Haven's bounty system.

Scope

• Explain the core insight: in emerging markets, a stolen phone sells to a fence for ~$15–$40. A bounty above fence price makes returning the device the rational choice.
• Include the bounty multiplier formula used in the frontend calculator
• Provide worked examples at different bounty levels ($50, $100, $250)
• Explain the USDC escrow mechanism and how funds are locked/released via the smart contract
• Discuss edge cases: what happens if no one claims, bounty expiry, and dispute resolution

Acceptance Criteria

• Clear explanation of the economic incentive model
• At least 3 worked examples with different bounty amounts
• Escrow lifecycle is documented (deposit → lock → claim → release)
• Page is linked from the GitBook sidebar under 'Protocol Design'

[Adamchaua]

Submitted PR: #10

Changes included:

• Added a new protocol-design/bounty-economics.md page explaining Haven's recovery-bounty incentive model.
• Included the bounty multiplier formula and worked examples for $50, $100, and $250 bounty levels.
• Documented the intended USDC escrow lifecycle: deposit -> lock -> claim -> release.
• Covered edge cases for no claim, bounty expiry, and dispute resolution.
• Linked the page from the GitBook sidebar under Protocol Design.

Verification:

• git diff --check
• Documentation-only change; no runtime tests required.

Payment wallet:
0x1ecab01075f3bdf1b56b7d849c8e28ef88943624

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