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/execute.md

@@ -318,7 +318,7 @@ const autoYes = $ARGUMENTS.includes('--yes') || $ARGUMENTS.includes('-y')
 if (autoYes) {
   // Auto mode: Complete session automatically
   console.log(`[--yes] Auto-selecting: Complete Session`)
-  SlashCommand("/workflow:session:complete --yes")
+  Skill(skill="workflow:session:complete", args="--yes")
 } else {
   // Interactive mode: Ask user
   AskUserQuestion({