⚡ Bolt: Optimize get_discovered_files query

[jspann21]

💡 What: Refactored the get_discovered_files SQLite query to use a Common Table Expression (CTE) for pagination.

🎯 Why: The original query performed a LEFT JOIN on enrichment_jobs and library_folders for all rows matching the WHERE clause before applying the LIMIT and OFFSET. This caused the database engine to do unnecessary work for rows that would eventually be discarded by pagination, causing an N+1 performance bottleneck.

📊 Impact: This change improves the performance of the get_discovered_files query, particularly when there is a large number of unresolved files, by deferring expensive joins until after the limit is applied. This reduces database CPU usage and memory consumption.

🔬 Measurement:

1. Run cargo test --manifest-path src-tauri/Cargo.toml to verify there are no SQL syntax regressions.
2. In the app, navigate to the "Unresolved Files" section with a large dataset and observe faster loading times for the grid/list.

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PR created automatically by Jules for task 3302304283058640519 started by @jspann21

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