Add roadmap: planar and surface topology

[mccorvie]

Summary

• Add a planar topology roadmap covering Jordan separation, surface triangulation, the two-dimensional Hauptvermutung, Schoenflies, and PL/smooth structure uniqueness.
• Add a surface topology roadmap covering generalized maps, finite presentations, surface classification, mapping class groups, and planarity.
• Connect the new roadmaps to the existing conformal mapping and geometric topology roadmaps.

Validation

• lake build
• git diff --check

AI assistance

OpenAI Codex (GPT-5) was used for repository setup, build diagnosis, mechanical formatting, and pull-request preparation.

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