feat(orchestrator): slice 2 — launch lifecycle + signed launch-broker (#352)

Second slice of PRD 0070, still a backend-neutral dev-harness:

  * orchestrator/broker.py — the launch-broker contract. A LaunchRequest is
    structured (static ids/flags only — bottle id, pool slot, a
    content-addressed image_ref; never a path/argv) and signed as a compact
    HS256 JWT so the broker verifies PROVENANCE before acting: a compromised
    co-located component can't forge a launch without the shared secret.
    verify_request is fail-closed (bad sig / malformed / off-schema -> raise).
    Stdlib only (no runtime deps). Ships a StubBroker that records verified
    requests for the harness/tests.
  * orchestrator/service.py — the Orchestrator: owns the registry and brokers
    the lifecycle. launch_bottle mints the bottle + sends a signed launch,
    rolling the registry entry back if the launch fails (no orphans);
    teardown_bottle brokers teardown then deregisters; attribute delegates.
  * control_plane.py — POST /bottles now launches, DELETE tears down (both go
    through the Orchestrator + broker). dispatch/server take an Orchestrator.
  * __main__.py wires an ephemeral secret + StubBroker for the harness.

Tests: broker sign/verify round-trip, tamper/wrong-secret/malformed/off-schema
rejection, StubBroker fail-closed; Orchestrator launch->registry->attribute,
teardown, rollback-on-broker-failure; control-plane updated for launch/teardown.
Full suite green (only the pre-existing /bin/sleep errors); harness does
launch -> attribute -> teardown over HTTP.

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

bot_bottle/orchestrator/__init__.py

@@ -7,23 +7,45 @@ backend-neutral "consolidation core" that needs no VM packaging:
 
   * `registry`      — the SQLite runtime-state store + fail-closed
                       attribution (source IP + per-bottle identity token).
-  * `control_plane` — the HTTP control-plane RPC (register / deregister /
-                      list / attribute / health), with live reload.
+  * `broker`        — the signed, structured launch-request contract + a
+                      `LaunchBroker` (stub for the harness) that verifies
+                      provenance before acting.
+  * `service`       — the `Orchestrator`: owns the registry, brokers the
+                      launch lifecycle (launch/teardown), attributes.
+  * `control_plane` — the HTTP control-plane RPC (launch / teardown /
+                      list / attribute / health).
 
-Launch/teardown, the launch broker, and the actual egress/git/supervise
-data plane land in later slices once this core is proven (see the PRD's
-sequencing: plain-process dev-harness -> docker orchestrator -> firecracker).
+The actual backend-native launch (a real docker/firecracker broker) and
+the egress/git/supervise data plane land in later slices once this core is
+proven (see the PRD sequencing: plain-process dev-harness -> docker
+orchestrator -> firecracker).
 """
 
 from __future__ import annotations
 
 from .registry import BottleRecord, RegistryStore, new_identity_token
+from .broker import (
+    BrokerAuthError,
+    LaunchBroker,
+    LaunchRequest,
+    StubBroker,
+    sign_request,
+    verify_request,
+)
+from .service import Orchestrator
 from .control_plane import ControlPlaneServer, dispatch, make_server
 
 __all__ = [
     "BottleRecord",
     "RegistryStore",
     "new_identity_token",
+    "BrokerAuthError",
+    "LaunchBroker",
+    "LaunchRequest",
+    "StubBroker",
+    "sign_request",
+    "verify_request",
+    "Orchestrator",
     "ControlPlaneServer",
     "dispatch",
     "make_server",