fix(collaboration): harden delegated task isolation (#1486)

* feat(collaboration): isolate delegated artifacts and child runs

Isolate delegated inputs and outputs behind secure artifact exchange lifecycles. Scope Agent Link tasks by tenant and root agent, and enforce delegation spawn-tree boundaries. Add process-wide child-run admission and preserve logical media paths across native, MCP, and sandbox execution.

* fix(collaboration): harden delegated task isolation

Enforce tenant and root-agent task scope across migrations and stores. Add exactly-once async completion delivery, delegated sandbox boundaries, and confined artifact and media recovery across runtime surfaces.

* fix(collaboration): recover interrupted async tasks

* fix(collaboration): normalize persisted child-run status

---------

Co-authored-by: ntduc <ntduc@cpp.ai.vn>

docs/01-agent-loop.md

@@ -111,7 +111,7 @@ Agents support three orchestration modes that determine which inter-agent tools
 - **Use case**: Agent with linked delegate targets
 - **Tools available**: `spawn`, `delegate` (dispatch to linked agents)
 - **Tools hidden**: `team_tasks`
-- **Resolution**: When `agent_links` table has rows with source = this agent
+- **Resolution**: When `agent_links` grants this agent an effective outbound delegation edge
 
 ### ModeTeam
 - **Use case**: Agent in a team (multiple agents collaborating)
@@ -121,7 +121,9 @@ Agents support three orchestration modes that determine which inter-agent tools
 
 **Mode Resolution Priority**: Team > Delegate > Spawn
 
-The system prompt includes relevant details for each mode (delegate targets, team context, shared workspace paths).
+The system prompt includes relevant details for each mode. Agent Team runs use
+their existing shared workspace. Agent Link runs receive only delegation-scoped
+`inputs/` and `outputs/` aliases.
 
 ---