Update coin exercises scaffolding for coin_registry

[alilloig]

Summary

Updates I1, I2, I3 coin exercises to use the new coin_registry standard while maintaining the scaffolded TODO structure for learners.

• Update imports to sui::coin_registry
• Maintain todo!() macros with clear task comments
• Add scaffolded tests demonstrating expected behavior

Changes

• I1/silver: Create currency and mint functions scaffolded
• I2/fixed_supply: Fixed supply pattern with coin_registry
• I3/king_credits: Multi-sig treasury with coin_registry

Companion to #176 (solution branch)

Part of SBF-256

🤖 Generated with Claude Code

[alilloig]

Code Review Summary

Critical Issues (Must Fix)

None identified - all packages build successfully and scaffolding is consistent with the solution branch.

Important Issues (Should Fix)

Documentation & Clarity (High Priority)

• Missing finalize_registration documentation - Students need context on this function's purpose
• Missing hint about coin_registry return type pattern - The new (CurrencyInitializer, TreasuryCap) pattern needs explanation
• Missing explanation of make_supply_fixed behavior - Students should understand the consequence of this call

Task Comment Improvements (Medium Priority)

• I3/king_credits task comment too dense - Break into numbered steps for clarity
• I2 multi-step tasks need numbered steps - Current format is harder to follow
• Mint task comment lacks context - Add brief explanation of the function's purpose

Scaffolding Consistency (Medium Priority)

• Inconsistent todo!() macro visibility between I1 and I2 (public vs private functions)
• Inconsistent scaffolding approach - I1 has todo in create_currency, I2 has it implemented
• Test test_mint contains todo!() - Consider whether tests should demonstrate expected behavior rather than require completion

Positive Notes

• All packages compile successfully
• Tests fail as expected due to todo!() macros - correct behavior for scaffolded code
• Scaffolding aligns well with solution branch (PR Migrate coin exercises to coin_registry standard #176)
• Overall structure provides a solid learning path

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🤖 Automated review by Claude Code

[alilloig]

Final Review - Issues Addressed

Fixed in this update

• test_mint calls the function directly (not todo!()) - Line 61 in I1/silver.move: let coin = mint(&mut tcap, amount, &mut ctx);
• todo!() macro visibility standardized - Both I1 and I2 use private macro (no public modifier)
• Numbered steps added to task comments in I2 and I3 - Steps 1-4 in I2, Steps 1-5 in I3
• Hints added about coin_registry return types - I1 has comment about (CurrencyInitializer<SILVER>, TreasuryCap<SILVER>) tuple
• Hints about function purposes (mint, make_supply_fixed) - I1 mint has usage hint, I2 explains make_supply_fixed behavior

Remaining items

None - all requested fixes have been applied.

Verification

• Build I1/silver: PASS (with expected unused warnings due to scaffolded todo!)
• Build I2/fixed_supply: PASS (with expected unused warnings due to scaffolded todo!)
• Build I3/king_credits: PASS (with expected unused warnings due to scaffolded todo!)
• Tests expected to fail due to scaffolded todo!() - this is correct for the main branch

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🤖 Final review by Claude Code