docs(asl): Upgrade Tool 3 architecture from Fan-out to Scatter+Aggregator (v2.0)

Architecture transformation:
- Replace Fan-out (Manager->Child->Last Child Wins) with Scatter+Aggregator pattern
- API layer directly dispatches N independent jobs (no Manager)
- Worker only writes its own Result row, never touches Task table (zero row-lock)
- Aggregator polls groupBy for completion + zombie cleanup (replaces Sweeper)
- Reduce red lines from 13 to 9, eliminate distributed complexity

Documents updated (10 files):
- 08-Tool3 main architecture doc: v2.0 rewrite (schema, Task 2.3/2.4, red lines, risks)
- 08d-Code patterns: rewrite sections 4.1-4.6 (API dispatch, SingleWorker, Aggregator)
- 08a-M1 sprint: rewrite M1-3 core (Worker+Aggregator), red lines, acceptance criteria
- 08b-M2 sprint: simplify SSE (NOTIFY/LISTEN downgraded to P2 optional)
- 08c-M3 sprint: milestone table wording update
- New: Scatter+Polling Aggregator pattern guide v1.1 (Level 2 cookbook)
- New: V2.0 architecture deep review and gap-fix report
- Updated: ASL module status, system status, capability layer index

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend-v2/src/modules/aia/styles/chat-workspace.css

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