Document coherent cohomology proof search

[Vilin97]

Summary

• reconstruct the coherent-cohomology run as a node-by-node proof-search graph
• classify decomposition, branching, backtracking, and operations that do not fit those idioms
• state the attempted goal at every node and link it to a sanitized trace index, key tool calls, and pinned surviving source
• link the new analysis and trace index from the project README

Validation

• git diff --cached --check
• verified all relative Markdown targets, reference labels, and trace anchors
• verified 84 indexed raw-trace locations and 16 recorded tool-call IDs against the session log in one streaming pass
• sensitive-pattern scan passed

Documentation-only change; no Lean build was run, to avoid unnecessary laptop load.