feat: Add new skills and templates for domain modeling, bug diagnosis, and architectural improvement

- Introduced a human-in-the-loop script for bug diagnosis to capture user feedback.
- Created ADR and CONTEXT formats to standardize architectural decision records and domain context documentation.
- Developed a domain modeling skill to refine terminology and maintain a shared language.
- Enhanced the improve-codebase-architecture skill to provide visual reports and deepening opportunities.
- Consolidated grilling and handoff skills for better user interaction and documentation.
- Updated existing skills to improve clarity and consistency in descriptions and functionality.

skills/productivity/README.md

@@ -2,8 +2,18 @@
 
 General workflow tools, not code-specific.
 
+## Commands
+
+User-invoked entry points (`disable-model-invocation: true`).
+
 - **[caveman](./caveman/SKILL.md)** — Ultra-compressed communication mode. Cuts token usage ~75% by dropping filler while keeping full technical accuracy.
 - **[grill-me](./grill-me/SKILL.md)** — Get relentlessly interviewed about a plan or design until every branch of the decision tree is resolved.
 - **[handoff](./handoff/SKILL.md)** — Compact the current conversation into a handoff document so another agent can continue the work.
 - **[teach](./teach/SKILL.md)** — Teach the user a new skill or concept over multiple sessions, using the current directory as a stateful teaching workspace.
 - **[write-a-skill](./write-a-skill/SKILL.md)** — Create new skills with proper structure, progressive disclosure, and bundled resources.
+
+## Skills
+
+Model- or user-invocable (rich trigger phrasing so the model can reach for them).
+
+- **[grilling](./grilling/SKILL.md)** — Interview the user relentlessly about a plan or design until every branch of the decision tree is resolved.