## Summary
Adds an LRU (Least Recently Used) cache layer and storage I/O utilities
that handle localStorage quota limits gracefully. When storage is full,
the oldest drafts are automatically evicted to make room for new ones.
## Changes
- **What**:
- `draftCacheV2.ts` - In-memory LRU cache with configurable max entries
(default 32)
- `storageIO.ts` - Storage read/write with automatic quota management
and eviction
- **Why**: Users experience `QuotaExceededError` when localStorage fills
up with workflow drafts, breaking auto-save functionality
## Review Focus
- LRU eviction logic in `draftCacheV2.ts`
- Quota error handling and recovery in `storageIO.ts`
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*Part 2 of 4 in the workflow persistence improvements stack*
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Co-authored-by: Amp <amp@ampcode.com>
