feat(git-gate+orchestrator): slice 13c(i) — per-bottle git-gate provisioning render

The consolidated gateway serves every bottle's repos under /git/<bottle_id>/
(slice 10), so each bottle's bare repos + per-repo credential config must be
provisioned into that namespace. This adds the renderer for that; placing
the creds + running it inside the gateway is the launch-wiring step.

- Extract the credential-wiring `init_repo` shell into a shared
  `_git_gate_init_repo_fn(repo_root, creds_dir)` — one source for the
  security-sensitive logic. The single-tenant daemon entrypoint is
  byte-unchanged (still /git + /git-gate/creds; existing tests green).
- git_gate_render_provision(bottle_id, upstreams): posix-sh that inits ONE
  bottle's bare repos under /git/<bottle_id>/ reading creds from
  /git-gate/creds/<bottle_id>/. Init-only (no `git daemon` — the shared
  gateway already serves). Isolating each bottle's repo root + creds dir by
  id is what keeps one bottle's push credentials out of another's repos.
- bottle_id is embedded unquoted in the script, so it's restricted to a
  shell/path-safe alphabet (registry ids are token_hex; defense in depth).

pyright 0 errors; pylint 9.83/10; unit suite green (1724 tests; the 13
test_sidecar_init /bin/sleep errors are pre-existing NixOS-local noise).

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

tests/unit/test_git_gate_provision_render.py

@@ -0,0 +1,67 @@
+"""Unit: consolidated per-bottle git-gate provisioning render (PRD 0070)."""
+
+from __future__ import annotations
+
+import unittest
+
+from bot_bottle.git_gate_render import (
+    GitGateUpstream,
+    git_gate_render_entrypoint,
+    git_gate_render_provision,
+)
+
+
+def _ups(*names: str) -> tuple[GitGateUpstream, ...]:
+    return tuple(
+        GitGateUpstream(
+            name=n,
+            upstream_url=f"ssh://git@github.com/x/{n}.git",
+            upstream_host="github.com",
+            upstream_port="22",
+            identity_file="",
+            known_host_key="",
+        )
+        for n in names
+    )
+
+
+class TestProvisionRender(unittest.TestCase):
+    def test_namespaces_repos_and_creds_by_bottle_id(self) -> None:
+        script = git_gate_render_provision("bottleab12", _ups("foo"))
+        self.assertIn("repo=/git/bottleab12/${name}.git", script)
+        self.assertIn("keyfile=/git-gate/creds/bottleab12/${name}-key", script)
+        self.assertIn("mkdir -p /git/bottleab12", script)
+
+    def test_one_init_repo_call_per_upstream(self) -> None:
+        script = git_gate_render_provision("b1", _ups("foo", "bar"))
+        calls = [l for l in script.splitlines() if l.startswith("init_repo ")]
+        self.assertEqual(2, len(calls))
+
+    def test_provision_does_not_start_the_daemon(self) -> None:
+        # The shared gateway already serves; provisioning is init-only.
+        self.assertNotIn("git daemon", git_gate_render_provision("b1", _ups("foo")))
+
+    def test_installs_pre_receive_hook(self) -> None:
+        script = git_gate_render_provision("b1", _ups("foo"))
+        self.assertIn("install -m 755 /etc/git-gate/pre-receive", script)
+
+    def test_rejects_unsafe_bottle_id(self) -> None:
+        for bad in ("../etc", "a/b", "a b", "a;rm", ""):
+            with self.assertRaises(ValueError):
+                git_gate_render_provision(bad, _ups("foo"))
+
+
+class TestEntrypointUnchanged(unittest.TestCase):
+    """The shared `_git_gate_init_repo_fn` refactor must not alter the
+    single-tenant daemon entrypoint's output."""
+
+    def test_entrypoint_still_single_tenant_flat(self) -> None:
+        script = git_gate_render_entrypoint(_ups("foo"))
+        self.assertIn("repo=/git/${name}.git", script)      # flat, not namespaced
+        self.assertIn("keyfile=/git-gate/creds/${name}-key", script)
+        self.assertIn("--base-path=/git", script)
+        self.assertIn("exec git daemon", script)
+
+
+if __name__ == "__main__":
+    unittest.main()