Major performance improvements for graph visualization:
Cache System:
- Add cache.lua module that stores parsed links/tags per file
- Only re-parse files that have been modified (mtime check)
- Cache stored in .ideadrop-graph-cache.json in idea_dir
- Fast file scanning using vim.fs.find when available
Layout Optimizations:
- Reduce max iterations from 300 to 100
- Faster convergence with adjusted parameters
- Barnes-Hut approximation for large graphs (100+ nodes)
- Cache math functions locally for speed
- Skip distant node pairs in repulsion calculation
- Reuse visible_nodes array across iterations
New Commands:
- :IdeaGraph rebuild - Force full cache rebuild
- :IdeaGraphClearCache - Clear cache file
This makes opening the graph nearly instant for previously
scanned vaults, similar to Obsidian's behavior.
