⚡ Bolt: Add module-level caching to BlogApp fetch

[schmug]

💡 What: Added module-level caching (fetchPromise and cachedPayload) for the /api/blog.json fetch request in BlogApp.tsx.
🎯 Why: To solve a performance issue where opening, closing, and reopening the BlogApp window caused redundant API calls and UI flashes while waiting for data that hadn't changed. This leverages the static nature of the API response.
📊 Impact: Reduces network requests by 100% for subsequent BlogApp opens within the same session. Decreases Time To Interactive (TTI) for repeated opens to effectively zero.
🔬 Measurement: Open the BlogApp, check the Network tab to see the initial blog.json fetch. Close the app and reopen it - no new fetch will occur, and the data renders instantly.

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PR created automatically by Jules for task 1812113323681097730 started by @schmug

[google-labs-jules]

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[schmug]

Superseded by #127 (merged to main), which consolidated the best of the duplicate Bolt/Sentinel/Palette scheduled-agent PRs into one reviewed change. Closing as duplicate.

[google-labs-jules]

Superseded by #127 (merged to main), which consolidated the best of the duplicate Bolt/Sentinel/Palette scheduled-agent PRs into one reviewed change. Closing as duplicate.

Understood. Acknowledging that this work is now obsolete as it has been superseded by #127. Stopping work on this task.