refactor: consolidate timelineProgress calculation into vaultLifecycl…

[A-one-tech]

#Closes
#743

PR: Extract shared timelineProgress helper and guard equal timestamps

Summary

Extracts the duplicate timelineProgress(created, deadline) utility function into src/utils/vaultLifecycle.ts and replaces the inline module-level implementations in both src/pages/Dashboard.tsx and src/pages/VaultDetail.tsx.

Also resolves an unguarded divide-by-zero issue where equal created and deadline timestamps resulted in (end - start) === 0 and returned NaN.

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Motivation & Problem Statement

• Code Duplication: Both Dashboard.tsx (line 42) and VaultDetail.tsx (line 51) maintained self-acknowledged identical implementations of timelineProgress.
• Edge-Case Bug: If a vault was configured with created === deadline, (end - start) equaled 0, leading to ((now - start) / 0) * 100 => NaN which propagated through Math.max / Math.min into UI progress bar rendering.

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Key Changes

1. src/utils/vaultLifecycle.ts

• Added and exported timelineProgress(created: string, deadline: string, now: number = Date.now()): number.
• Added guards for end <= start (returns 100 if now >= start, else 0) to prevent NaN divide-by-zero errors.
• Added guards for invalid date string inputs (returns 0).

2. src/pages/Dashboard.tsx & src/pages/VaultDetail.tsx

• Removed duplicate inline timelineProgress functions.
• Imported timelineProgress from ../utils/vaultLifecycle.

3. src/utils/__tests__/vaultLifecycle.test.ts

• Added comprehensive unit test suite covering:
  • Exact percentage calculation during vault lifetime (50% halfway point).
  • Clamping to 0% before creation date and 100% past deadline date.
  • Equal creation and deadline timestamps (created === deadline) returning 100 / 0 without NaN.
  • Inverted creation and deadline timestamps (deadline < created).
  • Invalid date string handling.

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Verification & Testing

Automated Test Execution

# Targeted utility tests
npx vitest run src/utils/__tests__/vaultLifecycle.test.ts

# Consuming page test suites
npx vitest run src/pages/__tests__/Dashboard.test.tsx src/pages/__tests__/VaultDetail.test.tsx

Test Results

• vaultLifecycle.test.ts: 11 passed (5 stages tests + 6 timelineProgress tests)
• Dashboard.test.tsx: 3 passed
• VaultDetail.test.tsx: 19 passed

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Checklist

• Extracted timelineProgress helper into src/utils/
• Imported shared helper in Dashboard.tsx and VaultDetail.tsx
• Added divide-by-zero / equal timestamp guard
• Added unit tests for edge cases and normal progress
• All tests passing locally

Closes #743

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[1nonlypiece]

Hi @A-one-tech, closing this for now — I don't see it linked to an issue that's assigned to you. Feel free to reopen (or open a fresh PR) once you're assigned to the issue it addresses.