[Contract] Royalty reduction, remove sunset, struct optimization (#38 Group A)

[realproject7]

Summary

Group A of #38. Three tightly coupled changes to StoryFactory.sol — royalty rate, sunset removal, and struct packing. These must be done together because struct layout changes affect all three.

Parent issue: #38

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Changes

1. Reduce Mint/Burn Royalty: 5% → 1%

// Before
uint16 public constant MINT_ROYALTY = 500;
uint16 public constant BURN_ROYALTY = 500;

// After
uint16 public constant MINT_ROYALTY = 100;
uint16 public constant BURN_ROYALTY = 100;

2. Remove sunset Variable — Derive from lastPlotTime

• Remove bool sunset from Storyline struct
• Remove require(!s.sunset, "Storyline sunset") from chainPlot()
• The deadline check already handles this: require(block.timestamp <= s.lastPlotTime + 168 hours, "Deadline passed")
• Add view function:

  function hasSunset(uint256 storylineId) external view returns (bool) {
      Storyline storage s = storylines[storylineId];
      return s.hasDeadline && block.timestamp > s.lastPlotTime + 168 hours;
  }

3. Struct Storage Optimization (5 slots → 2 slots)

struct Storyline {
    address writer;       // slot 1: 160 bits
    address token;        // slot 2: 160 bits
    uint24 plotCount;     // slot 2: +24 = 184 bits (max 16.7M plots)
    uint40 lastPlotTime;  // slot 2: +40 = 224 bits (max year 36,812)
    bool hasDeadline;     // slot 2: +8 = 232 bits
}

Update all references:

• plotCount: uint256 → uint24
• lastPlotTime: uint256 → uint40
• Cast block.timestamp to uint40 when assigning
• plotIndex in events can remain uint256

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Tests

• Update existing unit tests for removed sunset field
• Add test for hasSunset() view function
• Update royalty-related assertions if any exist
• Log gas comparison: before/after struct optimization
• forge test passes

Branch

task/{issue-number}-royalty-struct-sunset