Add live workflow permission brokering

[VikashLoomba]

Closes #381.

Summary

• add explicit AgentPrism omitted-mode defaults for built-in backends: Claude auto, Codex agent, OpenCode build, and no invented default for Pi/custom backends
• expose backend-advertised mode names, descriptions, metadata, option IDs, and ordering verbatim through config discovery and validate selected/default modes before prompting
• replace inferred permission persistence with exact advertised optionId decisions while retaining deprecated source-compatible helper shims
• add a live workflow permission broker that parks unresolved ACP requests and surfaces them from foreground run, inspect, and await results
• let elicitation-capable clients answer interactively and add action: "permissions-response" for other clients
• route permission responses to the daemon generation that owns the live ACP request and reject stale, invented, metadata-bearing, or otherwise invalid responses
• redact and bound public permission diagnostics to 64 KiB while preserving the complete ordered exact option set, or cancel fail-closed when a safe projection is impossible
• pause the backend-activity idle watchdog, but not total wall time, while a permission is pending
• keep workflows autonomous unless an author explicitly selects restrictive mode/tool policy

Validation

• pnpm test
• pnpm typecheck
• pnpm --filter @automatalabs/codex-acp test
• node scripts/check-acp-deps.mjs
• pnpm changeset status --since=origin/main
• node scripts/check-attribution.mjs origin/main..HEAD
• pre-push live Claude/Codex/OpenCode/pi and steering gates