fix: make installed wheel self-contained + harden install.sh prereqs

Addresses the review on PR #481.

Self-contained wheel (review point 1): the gateway/infra/orchestrator
images build from a context that must hold bot_bottle/, pyproject.toml,
and the root-level Dockerfiles. Modules previously located these by
walking __file__ to the repo root, so an installed wheel (package in
site-packages, no repo root) passed `doctor` but failed `start`.

- Add bot_bottle/resources.py: build_root() returns the repo root in a
  checkout (unchanged) or a staged copy from the wheel's bundled
  _resources/ otherwise; dockerfile()/nix_netpool_module()/
  netpool_script() derive from it.
- setup.py bundles the root Dockerfiles, nix module, netpool script, and
  pyproject.toml into bot_bottle/_resources/ at build; MANIFEST.in ships
  them in the sdist.
- Route every _REPO_ROOT/_REPO_DIR call site (docker/macos launch, macos
  infra, firecracker infra_vm/infra_artifact/setup, orchestrator
  lifecycle/gateway) through resources. Checkout behavior is unchanged.

install.sh prerequisites (review point 2): check for git when installing
a git+ spec, and — before the pip fallback — that pip is usable and the
interpreter isn't externally managed (PEP 668), pointing at pipx.

Tests: test_resources covers checkout + staged-wheel layouts;
test_wheel_install builds the wheel, installs it into an isolated venv,
and asserts `doctor` runs and build_root() yields a valid context.
Running `start` end-to-end still needs a Docker/KVM host (CI).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

bot_bottle/backend/docker/orchestrator.py

@@ -15,6 +15,7 @@ import time
 from pathlib import Path
 
 from ... import log
+from ... import resources
 from .util import run_docker
 from ...paths import (
     ORCHESTRATOR_TOKEN_ENV,
@@ -55,8 +56,6 @@ _ROOT_IN_CONTAINER = "/bot-bottle-root"
 
 _HEALTH_POLL_SECONDS = 0.25
 
-_REPO_ROOT = Path(__file__).resolve().parents[3]
-
 
 class DockerOrchestrator(Orchestrator):
     """The control plane as a single fixed-name container. `ensure_built` builds
@@ -71,7 +70,7 @@ class DockerOrchestrator(Orchestrator):
         label: str = ORCHESTRATOR_LABEL,
         port: int = DEFAULT_PORT,
         control_network: str = ORCHESTRATOR_NETWORK,
-        repo_root: Path = _REPO_ROOT,
+        repo_root: Path | None = None,
         host_root: Path | None = None,
         dockerfile: str | None = ORCHESTRATOR_DOCKERFILE,
     ) -> None:
@@ -80,7 +79,9 @@ class DockerOrchestrator(Orchestrator):
         self.label = label
         self.port = port
         self.control_network = control_network
-        self._repo_root = repo_root
+        # Build context / bind-mount source: the repo root in a checkout, a
+        # staged copy from the installed wheel otherwise (bot_bottle.resources).
+        self._repo_root = repo_root if repo_root is not None else resources.build_root()
         self._host_root = host_root or bot_bottle_root()
         self._dockerfile = dockerfile