fix: remove dead hooks, add multi-space workflows, polish pseudo-code

[tipuq]

Changes

Must fix

• Deleted hook scripts (aws-allow-chat.sh, aws-allow-reads.sh) — dead code. The hook engine lacks stdin passthrough and MCP tool name matching, so these never fire. POWER.md already acknowledged this limitation.
• Removed hook directory reference from POWER.md ("Pre-written scripts are in .kiro/hooks/...")

Should fix

• Added Multi-AgentSpace Workflows section to POWER.md — routing table (single/parallel/ambiguous) + parallel pattern example with 2 spaces
• Added Multi-AgentSpace Routing rules to steering.md — when to fan out, when to ask, timeout handling, synthesis guidance

Nice to have

• Added pseudo-code shorthand note — first call_boto3(SendMessage, params={...}) occurrence now notes it's shorthand for the full await call_boto3(service_name=..., operation_name=..., params={...}) form