chore: restructure collab into questions/proposals/plan subdirs; update references

AGENTS.md

@@ -3,10 +3,10 @@
 Scope: Applies to the entire repository unless overridden by a deeper AGENTS.md.
 
 ## Collaboration Artifacts
-- Directory: `collab/`
-- Naming: `<step-or-subject>-<type>.md`
-  - Examples: `00-bootstrap-questions.md`, `01-wrapper-proposal.md`, `01-wrapper-plan.md`
-- Types: `questions`, `proposal`, `plan`
+- Root: `collab/`
+- Subdirectories: `collab/questions/`, `collab/proposals/`, `collab/plan/`
+- Naming: `<step-or-subject>.md` inside each subdirectory
+  - Examples: `collab/questions/00-bootstrap.md`, `collab/proposals/01-wrapper.md`, `collab/plan/01-wrapper.md`
 - Principle: Keep chat minimal; prefer file-based collaboration via these documents.
 
 ## Logs and Documentation
@@ -32,4 +32,3 @@ Scope: Applies to the entire repository unless overridden by a deeper AGENTS.md.
 - Ask clarifying questions in `collab/<...>-questions.md`.
 - Propose in `collab/<...>-proposal.md`, plan in `collab/<...>-plan.md`, then implement.
 - Respect repository structure and this AGENTS.md across all changes.
-