feat(crowdfund): add affiliate links and referral tracking (#349)

[Ebenezer199914]

Implement affiliate/referral tracking for crowdfund campaigns so that campaign organizers can register affiliates, distribute unique referral codes, and reward affiliates with an on-chain commission whenever a contributor uses their code.

Changes

contracts/crowdfund/src/errors.rs

• AffiliateNotRegistered (28) – caller not registered as an affiliate
• ReferralCodeAlreadyTaken (29) – code owned by a different affiliate
• InvalidCommissionBps (30) – bps value exceeds 10 000
• ReferralCodeNotFound (31) – no affiliate for the supplied code
• ReferralAlreadyUsed (32) – contributor already used a referral code

contracts/crowdfund/src/lib.rs

New DataKey variants:
AffiliateCommissionBps, ReferralCodeOwner(BytesN<32>), AffiliateCode(Address), ReferralCount(BytesN<32>), ReferralEarnings(BytesN<32>), PledgeReferral(Address)

New events:
AffiliateRegisteredEvent, ReferralUsedEvent

New public functions:
set_affiliate_commission – organizer sets campaign-wide commission bps
register_affiliate – organizer maps affiliate ↔ code_hash
contribute_with_referral – contribute + validate code + pay commission
get_referral_count – unique contributors who used a code
get_referral_earnings – cumulative commission earned by code
get_referral_code – affiliate address → code hash lookup
get_contributor_referral – contributor → used code lookup
get_affiliate_commission_bps – current commission rate

Bug fix:
Added missing #[contractevent] macro to PledgeReceivedEvent (CICB bug)

contracts/crowdfund/src/test.rs

24 new tests covering:

• set_affiliate_commission happy-path and bounds validation
• register_affiliate idempotency, duplicate-code conflict
• contribute_with_referral: raised amount, commission transfer, referral count, earnings accumulation, contributor recording
• Error paths: invalid code, double-referral, past deadline, zero amt
• Zero-commission edge case
• Integration with matching pool
• Campaign execution after referral contributions

All 83 tests pass.

Description

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Test improvements
• Other (please describe):

Related Issues

Fixes #

Changes Made

Testing

• I have added tests that prove my fix is effective or that my feature works
• All existing tests pass locally
• I have tested this manually

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published

Screenshots (if applicable)

Additional Notes

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Issue	Title
#349	Implement Affiliate Links and Referral Tracking for Campaigns	Link to this issue

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