docs(prd): 0070 per-host orchestrator service

Fold the per-bottle sidecar bundle into a single persistent per-host
orchestrator: runs the sidecar functions (egress/git-gate/supervise),
coordinates with the console, and brokers agent launches. Virtualized
from the start with backend-native isolation (fc VM / apple ctr / docker
ctr), fronted by a single backend-agnostic contract; per-backend
variation lives on BottleBackend, not a parallel Orchestrator hierarchy.

Leads with the security review (secret concentration, shared fate, the
launch-broker-as-new-privileged-core, and the source-IP attribution
invariant each backend must enforce). Proposes one SQLite DB owned by the
orchestrator for runtime state (slot leases, approvals, registry) —
distinct from build-time constants (flat .env) and user config
(declarative ~/.bot-bottle). Sequences docker -> firecracker -> macos,
developing the service as a plain-process dev-harness before the VM.

Supersedes 0069's Stage-1/4 sidecar framing; depends on 0069's nix-built
fixed images. Tracking issue #351.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck

docs/prds/0069-firecracker-native-docker-free.md

@@ -1,10 +1,16 @@
 # PRD 0069: Firecracker-native, Docker-free backend
 
-- **Status:** Draft
+- **Status:** Draft (partially superseded)
 - **Author:** Claude
 - **Created:** 2026-07-12
 - **Issue:** #348
 
+> **Superseded in part by [PRD 0070](0070-per-host-orchestrator.md) (#351):**
+> the sidecar-consolidation framing here (Stage 1, per-host sidecar; Stage 4,
+> sidecar-as-VM) is taken over by 0070's per-host orchestrator. This PRD still
+> owns the docker-free **image-building** work — Stage 2 (nix-built fixed
+> images, a dependency of 0070) and Stage 3 (in-VM Dockerfile builder).
+
 ## Summary
 
 Make the Firecracker backend depend on **firecracker + KVM only**, removing