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/skills/team-lifecycle/subagents/explore-subagent.md

@@ -14,7 +14,7 @@ Results were scattered across different directories and never shared. In v4, all
 ## Invocation
 
 ```
-Task({
+Agent({
   subagent_type: "cli-explore-agent",
   run_in_background: false,
   description: "Explore <angle>",
@@ -135,9 +135,10 @@ For complex queries, call cli-explore-agent per angle. The calling role determin
 
 ```
 # After seed analysis, explore codebase context
-Task({
+Agent({
   subagent_type: "cli-explore-agent",
   description: "Explore general context",
+  run_in_background: false,
   prompt: "Explore codebase for: <topic>\nFocus angle: general\n..."
 })
 # Result feeds into discovery-context.json
@@ -148,9 +149,10 @@ Task({
 ```
 # Multi-angle exploration before plan generation
 for angle in selected_angles:
-  Task({
+  Agent({
     subagent_type: "cli-explore-agent",
     description: "Explore <angle>",
+    run_in_background: false,
     prompt: "Explore codebase for: <task>\nFocus angle: <angle>\n..."
   })
 # Explorations manifest built from cache-index.json