fix: support @-target in {computed} for per-iteration values (#140)

[rohal12]

Summary

• Published types sync (feat(types): sync published types with source StoryAPI #135): Hand-update types/index.d.ts with ~17 missing StoryAPI members + compile-time drift-detection test
• Transient variables (Feature: transient variables — reactive but excluded from history snapshots #137): New % sigil for reactive variables excluded from persistence, routed through tokenizer, expression engine, store, rendering, and published types
• Computed + for-loop infinite loop ({computed} referencing @ loop variable inside {for} causes infinite reactive loop #140): Memoize ForIteration/WidgetBody local state to prevent infinite reactive loops when {computed} reads @ locals
• Computed @-target ({computed} referencing @ loop variable inside {for} causes infinite reactive loop #140 reopened): Extend {computed} to accept @var targets that write to per-iteration local scope via LocalsUpdateContext, fixing shared values across {for} iterations

Test plan

• npx vitest run — 1087 tests pass
• npx tsc --noEmit — typecheck clean
• Verify {computed @cls = @item.status == 'ok' ? 'green' : 'red'} inside {for} produces per-iteration values
• Verify {computed _cls = ...} inside {for} still works (last-write-wins, no hang)
• Verify {computed @cls = ...} outside a local scope logs an error

🤖 Generated with Claude Code

[github-actions]

Release preview: merging this PR will publish v0.43.2 (patch bump from v0.43.1)

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	77.39%	2831 / 3658
🔵	Statements	76.38%	3093 / 4049
🔵	Functions	69%	512 / 742
🔵	Branches	73.31%	1541 / 2102

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
src/components/macros/Computed.tsx	78.33%	77.5%	100%	81.13%	13, 14, 17-18, 20, 26-28, 35-37, 48-51, 74-78, 111-115

Generated in workflow #218 for commit d8b27c3 by the Vitest Coverage Report Action