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.md

@@ -2,7 +2,7 @@
 name: issue:discover
 description: Discover potential issues from multiple perspectives (bug, UX, test, quality, security, performance, maintainability, best-practices) using CLI explore. Supports Exa external research for security and best-practices perspectives.
 argument-hint: "[-y|--yes] <path-pattern> [--perspectives=bug,ux,...] [--external]"
-allowed-tools: Skill(*), TodoWrite(*), Read(*), Bash(*), Task(*), AskUserQuestion(*), Glob(*), Grep(*)
+allowed-tools: Skill(*), TodoWrite(*), Read(*), Bash(*), Agent(*), AskUserQuestion(*), Glob(*), Grep(*)
 ---
 
 ## Auto Mode
@@ -185,7 +185,7 @@ Launch N agents in parallel (one per selected perspective):
 ```javascript
 // Launch agents in parallel - agents write JSON and return summary
 const agentPromises = selectedPerspectives.map(perspective =>
-  Task({
+  Agent({
     subagent_type: "cli-explore-agent",
     run_in_background: false,
     description: `Discover ${perspective} issues`,
@@ -322,7 +322,7 @@ if (response === "Export to Issues") {
 **Perspective Analysis Agent**:
 
 ```javascript
-Task({
+Agent({
   subagent_type: "cli-explore-agent",
   run_in_background: false,
   description: `Discover ${perspective} issues`,
@@ -368,7 +368,7 @@ Task({
 **Exa Research Agent** (for security and best-practices):
 
 ```javascript
-Task({
+Agent({
   subagent_type: "cli-explore-agent",
   run_in_background: false,
   description: `External research for ${perspective} via Exa`,