chore: add CLAUDE.md agent guidance (+ AGENTS.md/GEMINI.md symlinks)

[rahlk]

Expands CLAUDE.md into full agent guidance for canpy, mirroring the setup in codeanalyzer-typescript:

• What this project is — the CLDK Python backend (Jedi symbol table + two-level Jedi/PyCG call graph, Neo4j projection).
• Architecture — the Codeanalyzer.analyze() pipeline in core.py, stage by stage.
• Directory map, Commands (uv / pytest / schema + README codegen), working conventions, the teaching-loop philosophy, and the release-announcement upkeep task (preserved from the previous CLAUDE.md).

Also symlinks AGENTS.md and GEMINI.md → CLAUDE.md (force-added past the global AGENTS.md gitignore) so AGENTS.md-aware agents and Gemini read the same file.

Closes #65

[rahlk]

Superseded: the agent guidance this PR drafted landed (in much-expanded, schema-v2-aware form) via 3ccaacd and the v2 chain released in 1.0.0 — main now has CLAUDE.md with AGENTS.md symlinked to it. The remaining piece, the GEMINI.md symlink, just merged in #103, which closes #65. This branch's June draft predates schema v2 and is now stale.