refactor(commands): replace SlashCommand with Skill tool invocation

Update all workflow command files to use Skill tool instead of SlashCommand:
- Change allowed-tools: SlashCommand(*) → Skill(*)
- Convert SlashCommand(command="/path", args="...") → Skill(skill="path", args="...")
- Update descriptive text references from SlashCommand to Skill
- Remove javascript language tags from code blocks (25 files)

Affected 25 command files across:
- workflow: plan, execute, init, lite-plan, lite-fix, etc.
- workflow/test: test-fix-gen, test-cycle-execute, tdd-plan, tdd-verify
- workflow/review: review-cycle-fix, review-module-cycle, review-session-cycle
- workflow/ui-design: codify-style, explore-auto, imitate-auto
- workflow/brainstorm: brainstorm-with-file, auto-parallel
- issue: discover, discover-by-prompt, plan
- ccw, ccw-debug

This aligns with the actual Skill tool interface which uses 'skill' and 'args' parameters.

.claude/commands/workflow/plan-verify.md

@@ -339,7 +339,7 @@ const canExecute = recommendation !== 'BLOCK_EXECUTION'
 // Auto mode
 if (autoYes) {
   if (canExecute) {
-    SlashCommand("/workflow:execute --yes --resume-session=\"${session_id}\"")
+    Skill(skill="workflow:execute", args="--yes --resume-session=\"${session_id}\"")
   } else {
     console.log(`[--yes] BLOCK_EXECUTION - Fix ${critical_count} critical issues first.`)
   }
@@ -370,8 +370,8 @@ const selection = AskUserQuestion({
 
 // Handle selection
 if (selection.includes("Execute")) {
-  SlashCommand("/workflow:execute --resume-session=\"${session_id}\"")
+  Skill(skill="workflow:execute", args="--resume-session=\"${session_id}\"")
 } else if (selection === "Re-verify") {
-  SlashCommand("/workflow:plan-verify --session ${session_id}")
+  Skill(skill="workflow:plan-verify", args="--session ${session_id}")
 }
 ```