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/engineering/tdd/SKILL.md

@@ -44,14 +44,13 @@ RIGHT (vertical):
 
 ### 1. Planning
 
-When exploring the codebase, use the project's domain glossary so that test names and interface vocabulary match the project's language, and respect ADRs in the area you're touching.
+When exploring the codebase, read `CONTEXT.md` (if it exists) so that test names and interface vocabulary match the project's domain language, and respect ADRs in the area you're touching.
 
 Before writing any code:
 
 - [ ] Confirm with user what interface changes are needed
 - [ ] Confirm with user which behaviors to test (prioritize)
-- [ ] Identify opportunities for [deep modules](deep-modules.md) (small interface, deep implementation)
-- [ ] Design interfaces for [testability](interface-design.md)
+- [ ] Identify opportunities for deep modules (small interface, deep implementation) — run the `/codebase-design` skill for the vocabulary and the testability checks
 - [ ] List the behaviors to test (not implementation steps)
 - [ ] Get user approval on the plan
 

skills/engineering/tdd/deep-modules.md

@@ -1,33 +0,0 @@
-# Deep Modules
-
-From "A Philosophy of Software Design":
-
-**Deep module** = small interface + lots of implementation
-
-```
-┌─────────────────────┐
-│   Small Interface   │  ← Few methods, simple params
-├─────────────────────┤
-│                     │
-│                     │
-│  Deep Implementation│  ← Complex logic hidden
-│                     │
-│                     │
-└─────────────────────┘
-```
-
-**Shallow module** = large interface + little implementation (avoid)
-
-```
-┌─────────────────────────────────┐
-│       Large Interface           │  ← Many methods, complex params
-├─────────────────────────────────┤
-│  Thin Implementation            │  ← Just passes through
-└─────────────────────────────────┘
-```
-
-When designing interfaces, ask:
-
-- Can I reduce the number of methods?
-- Can I simplify the parameters?
-- Can I hide more complexity inside?

skills/engineering/tdd/interface-design.md

@@ -1,31 +0,0 @@
-# Interface Design for Testability
-
-Good interfaces make testing natural:
-
-1. **Accept dependencies, don't create them**
-
-   ```typescript
-   // Testable
-   function processOrder(order, paymentGateway) {}
-
-   // Hard to test
-   function processOrder(order) {
-     const gateway = new StripeGateway();
-   }
-   ```
-
-2. **Return results, don't produce side effects**
-
-   ```typescript
-   // Testable
-   function calculateDiscount(cart): Discount {}
-
-   // Hard to test
-   function applyDiscount(cart): void {
-     cart.total -= discount;
-   }
-   ```
-
-3. **Small surface area**
-   - Fewer methods = fewer tests needed
-   - Fewer params = simpler test setup