docs: reorganize and source-verify the lending wiki Introduce a concepts-to-actions reading path and focused guides for account health, interest, positions, flash loans, strategies, vault integration, and oracle configuration. Preserve existing page URLs and replace stale protocol, governance, and verification claims with source-checked behavior. Validated against published source 913b28ca3d4cbe5358f543877bbee04a0eeb1315: 22 content pages, 255 wiki/source references, worked examples, Markdown structure, and independent financial/authorization reviews.