refactor(contract-validator): extract skills from commands

Extract shared knowledge from 5 command files into 6 reusable skills:
- plugin-discovery.md: Plugin scanning and discovery
- interface-parsing.md: README.md and CLAUDE.md parsing
- dependency-analysis.md: MCP server and data flow analysis
- validation-rules.md: Compatibility and agent validation
- mcp-tools-reference.md: Available MCP tools
- visual-output.md: Standard formatting and headers

Slim commands from 263-164 lines down to 44-55 lines each.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/clarity-assist/skills/4d-methodology.md

@@ -0,0 +1,76 @@
+# 4-D Methodology for Prompt Clarification
+
+The 4-D methodology transforms vague requests into actionable specifications.
+
+## Phase 1: Deconstruct
+
+Break down the user's request into components:
+
+1. **Extract explicit requirements** - What was directly stated
+2. **Identify implicit assumptions** - What seems assumed but not stated
+3. **Note ambiguities** - Points that could go multiple ways
+4. **List dependencies** - External factors that might affect implementation
+
+## Phase 2: Diagnose
+
+Analyze gaps and potential issues:
+
+1. **Missing information** - What do we need to know?
+2. **Conflicting requirements** - Do any stated goals contradict?
+3. **Scope boundaries** - What is in/out of scope?
+4. **Technical constraints** - Platform, language, architecture limits
+
+## Phase 3: Develop
+
+Gather clarifications through structured questioning:
+
+- Present 2-4 concrete options (never open-ended alone)
+- Include "Other" for custom responses
+- Ask 1-2 questions at a time maximum
+- Provide brief context for why you are asking
+- Check for conflicts with previous answers
+
+**Example Format:**
+```
+To help me understand the scope better:
+
+**How should errors be handled?**
+1. Silent logging (user sees nothing)
+2. Toast notifications (brief, dismissible)
+3. Modal dialogs (requires user action)
+4. Other
+
+[Context: This affects both UX and how much error-handling code we need]
+```
+
+## Phase 4: Deliver
+
+Produce the refined specification:
+
+```markdown
+## Clarified Request
+
+### Summary
+[1-2 sentence description of what will be built]
+
+### Scope
+**In Scope:**
+- [Item 1]
+- [Item 2]
+
+**Out of Scope:**
+- [Item 1]
+
+### Requirements
+
+| # | Requirement | Priority | Notes |
+|---|-------------|----------|-------|
+| 1 | ... | Must | ... |
+| 2 | ... | Should | ... |
+
+### Assumptions
+- [Assumption made based on conversation]
+
+### Open Questions
+- [Any remaining ambiguities, if any]
+```