refactor: replace Task tool with Agent tool and fix schema compliance

## Task -> Agent Replacement
- Replace all Task({}) calls with Agent({}) across .claude/ directory
- Update allowed-tools declarations from Task to Agent
- Update documentation references from "Task tool" to "Agent tool"

## Schema Compliance Fixes

### Agent Schema
- Add missing required `description` parameter in 6 files
- Add missing `run_in_background: false` for subagent calls
- Add missing `subagent_type` parameter

### AskUserQuestion Schema
- Fix issue-manage/SKILL.md: reduce options from 5 to 4 (max allowed)

### SendMessage Schema
- Fix team-worker.md: use correct params (type, content, summary)
- Remove invalid `team_name` parameter

### TaskCreate/TaskUpdate Schema
- Remove invalid `blockedBy`, `owner`, `status` from TaskCreate calls
- Use separate TaskUpdate calls for dependencies and ownership
- Fix TaskUpdate syntax to use object parameter

### TeamDelete Schema
- Remove parameters from TeamDelete() calls (should be no params)

### TaskOutput Schema
- Fix Python-style syntax to JavaScript object syntax

## Files Changed
- 146 files updated across commands/, skills/, skills_lib/, agents/

.claude/commands/issue/discover-by-prompt.md

@@ -2,7 +2,7 @@
 name: issue:discover-by-prompt
 description: Discover issues from user prompt with Gemini-planned iterative multi-agent exploration. Uses ACE semantic search for context gathering and supports cross-module comparison (e.g., frontend vs backend API contracts).
 argument-hint: "[-y|--yes] <prompt> [--scope=src/**] [--depth=standard|deep] [--max-iterations=5]"
-allowed-tools: Skill(*), TodoWrite(*), Read(*), Bash(*), Task(*), AskUserQuestion(*), Glob(*), Grep(*), mcp__ace-tool__search_context(*), mcp__exa__search(*)
+allowed-tools: Skill(*), TodoWrite(*), Read(*), Bash(*), Agent(*), AskUserQuestion(*), Glob(*), Grep(*), mcp__ace-tool__search_context(*), mcp__exa__search(*)
 ---
 
 ## Auto Mode
@@ -404,7 +404,7 @@ while (shouldContinue && iteration < maxIterations) {
 
   // Step 3: Launch dimension agents with ACE context
   const agentPromises = iterationPlan.dimensions.map(dimension =>
-    Task({
+    Agent({
       subagent_type: "cli-explore-agent",
       run_in_background: false,
       description: `Explore ${dimension.name} (iteration ${iteration})`,