feat: region metadata, integrity hash, owner review guard, and event snapshot tests

[gidson5]

Summary

• Add Project Region Metadata #238 — Added optional project region metadata via set_project_region / get_project_region (owner-only setter; stored under ExtensionKey::ProjectRegion).
• Add Review Eligibility Based on Project Ownership #245 — Project owners can no longer review their own project. add_review now returns ContractError::OwnerCannotReview (code 57) when reviewer == project.owner.
• Add Project Integrity Hash #250 — Added SHA-256 integrity hash over name|slug|category|description computed on every register_project and update_project call; stored under ExtensionKey::ProjectIntegrityHash and exposed via get_project_integrity_hash.
• Add Snapshot Tests for Events #258 — Added snapshot tests covering project registered, review submitted, fee set, admin added/removed, verification requested/approved, and review deleted-by-admin events. Also added snapshot_owner_cannot_review_own_project test. New region_and_integrity.rs test module validates Add Project Region Metadata #238 and Add Project Integrity Hash #250 behaviour.

Closes

Closes #238
Closes #245
Closes #250
Closes #258

Test plan

• snapshot_project_registered_event_shape — verifies event topics and payload fields
• snapshot_fee_set_event_shape — verifies fee config event
• snapshot_admin_added_and_removed_event_shape — verifies admin lifecycle events
• snapshot_verification_requested_and_approved_event_shape — verifies verification events
• snapshot_review_deleted_by_admin_event_shape — verifies admin moderation event
• snapshot_owner_cannot_review_own_project — owner review blocked
• test_region_is_none_by_default / test_owner_can_set_and_get_region / test_owner_can_clear_region / test_non_owner_cannot_set_region
• test_integrity_hash_set_on_registration / test_integrity_hash_changes_on_update

🤖 Generated with Claude Code

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