kan built card names with a serial number and wrote them to content/kanban/<kind>/, a folder this repo does not use, so every run failed.

Kan Writes into Per Kind Folders

• New cards land in a stage folder, defaulting to 01-to-do.
• Card names are p<priority>-<prefix>-<slug>.md; the serial number is gone.
• The ID (<prefix>-<slug>) is checked against every stage before writing.
• Hugo’s filename-derived title: is rewritten into a readable title.
• Tests cover kind deduction, stages, slugs, ID collisions and tidy-ups.

Acceptance Criteria

• go test ./cmd/kan passes.
• go run ./cmd/kan rq hunt the wumpus creates content/kanban/01-to-do/p2-rq-hunt-the-wumpus.md, and that card shows up in the requests table of the specification summary page.
• A taken ID, an unknown kind, an unknown stage, a priority outside 0-9 and a title over 40 characters all exit non-zero.
• The “not working” notices are gone from AGENTS.md, README.md and .pi/skills/kanban-card/SKILL.md, along with the serial-number wording in content/specification/personal-website/ideation.md.