feat: fold bot-bottle-orchestrator into bot_bottle/orchestrator subpackage

Moves the orchestrator into bot_bottle/orchestrator/ so one install gets
everything. Entry point is now `python -m bot_bottle.orchestrator run`.

- Add bot_bottle/orchestrator/ with all 14 modules (verbatim move; internal
  imports were already relative, so no changes inside orchestrator modules)
- Rewrite bootstrap.py: remove the lazy bot_bottle import guard, use direct
  relative imports from ..contrib.*
- Add bot_bottle/contrib/forge/base.py: ScopedForge (read-anywhere / write-scoped)
- Add bot_bottle/contrib/gitea/client.py: GiteaClient + GiteaForge (urllib.request only)
- Add bot_bottle/contrib/gitea/forge_state.py: ForgeState + SqliteForgeStateStore
- Add tests/unit/orchestrator/ (82 tests: 63 migrated + 19 new for contrib modules)

Closes #321

tests/unit/orchestrator/test_webhook.py

@@ -0,0 +1,155 @@
+"""Unit: webhook HTTP surface (signature + routing over a real server)."""
+
+from __future__ import annotations
+
+import hashlib
+import hmac
+import json
+import threading
+import unittest
+import urllib.request
+from urllib.error import HTTPError
+
+from bot_bottle.orchestrator.model import RunRecord
+from bot_bottle.orchestrator.store import InMemoryStateStore
+from bot_bottle.orchestrator.webhook import WebhookServer, verify_signature
+
+_ISSUE_ASSIGNED = {
+    "action": "assigned",
+    "repository": {"name": "bot-bottle", "owner": {"login": "didericis"}},
+    "issue": {
+        "number": 17, "title": "t", "body": "b",
+        "assignees": [{"login": "agent-bot"}],
+        "labels": [{"name": "bot-bottle:impl"}],
+    },
+}
+
+
+class _RecordingOrch:
+    def __init__(self) -> None:
+        self.events: list[object] = []
+
+    def handle(self, event: object) -> None:
+        self.events.append(event)
+
+
+class SignatureTest(unittest.TestCase):
+    def test_verify(self):
+        secret = b"s3cret"
+        body = b'{"x":1}'
+        sig = hmac.new(secret, body, hashlib.sha256).hexdigest()
+        self.assertTrue(verify_signature(secret, body, sig))
+        self.assertFalse(verify_signature(secret, body, "deadbeef"))
+
+
+class WebhookServerTest(unittest.TestCase):
+    # _serve is the per-test setup; attributes are assigned there.
+    # pylint: disable=attribute-defined-outside-init
+    def _serve(self, **kwargs: object) -> None:
+        self.orch = _RecordingOrch()
+        kwargs.setdefault("store", InMemoryStateStore())
+        self.server = WebhookServer(
+            ("127.0.0.1", 0), orchestrator=self.orch, **kwargs,  # type: ignore[arg-type]
+        )
+        self.port = self.server.server_address[1]
+        self.thread = threading.Thread(target=self.server.serve_forever, daemon=True)
+        self.thread.start()
+        self.addCleanup(self._shutdown)
+
+    def _shutdown(self) -> None:
+        self.server.shutdown()
+        self.server.server_close()
+        self.thread.join(timeout=5)
+
+    def _post(
+        self, path: str, body: bytes, headers: dict[str, str] | None = None
+    ) -> tuple[int, dict[str, object]]:
+        req = urllib.request.Request(
+            f"http://127.0.0.1:{self.port}{path}", data=body, method="POST",
+            headers=headers or {},
+        )
+        with urllib.request.urlopen(req, timeout=5) as resp:
+            return resp.status, json.loads(resp.read())
+
+    def _get(self, path: str) -> tuple[int, dict[str, object]]:
+        with urllib.request.urlopen(f"http://127.0.0.1:{self.port}{path}", timeout=5) as r:
+            return r.status, json.loads(r.read())
+
+    def test_webhook_dispatches(self):
+        self._serve()
+        body = json.dumps(_ISSUE_ASSIGNED).encode()
+        status, payload = self._post("/webhook", body, {"X-Gitea-Event": "issues"})
+        self.assertEqual(200, status)
+        self.assertTrue(payload["handled"])
+        self.assertEqual(1, len(self.orch.events))
+
+    def test_unhandled_event_ok_but_not_handled(self):
+        self._serve()
+        body = json.dumps({"action": "push"}).encode()
+        _status, payload = self._post("/webhook", body, {"X-Gitea-Event": "push"})
+        self.assertFalse(payload["handled"])
+        self.assertEqual([], self.orch.events)
+
+    def test_invalid_json_400(self):
+        self._serve()
+        with self.assertRaises(HTTPError) as ctx:
+            self._post("/webhook", b"{not json", {"X-Gitea-Event": "issues"})
+        self.assertEqual(400, ctx.exception.code)
+
+    def test_bad_signature_rejected(self):
+        self._serve(secret=b"sekret")
+        body = json.dumps(_ISSUE_ASSIGNED).encode()
+        with self.assertRaises(HTTPError) as ctx:
+            self._post("/webhook", body,
+                       {"X-Gitea-Event": "issues", "X-Gitea-Signature": "deadbeef"})
+        self.assertEqual(401, ctx.exception.code)
+        self.assertEqual([], self.orch.events)
+
+    def test_good_signature_accepted(self):
+        self._serve(secret=b"sekret")
+        body = json.dumps(_ISSUE_ASSIGNED).encode()
+        sig = hmac.new(b"sekret", body, hashlib.sha256).hexdigest()
+        status, _payload = self._post(
+            "/webhook", body, {"X-Gitea-Event": "issues", "X-Gitea-Signature": sig})
+        self.assertEqual(200, status)
+        self.assertEqual(1, len(self.orch.events))
+
+    def test_healthz(self):
+        self._serve()
+        self.assertEqual(200, self._get("/healthz")[0])
+
+    def test_unknown_path_404(self):
+        self._serve()
+        with self.assertRaises(HTTPError) as ctx:
+            self._post("/nope", b"{}", {"X-Gitea-Event": "issues"})
+        self.assertEqual(404, ctx.exception.code)
+
+    def test_provenance_returns_record_and_ops(self):
+        store = InMemoryStateStore()
+        store.upsert(RunRecord(owner="didericis", repo="bot-bottle", issue_number=17,
+                               slug="impl-17", agent_name="impl", bottle_names=["claude"]))
+
+        def reader(rec: object) -> list[dict[str, object]]:  # pylint: disable=unused-argument
+            return [{"at": "T", "op": "post_comment", "target": 17, "detail": "ok"}]
+
+        self._serve(store=store, op_log_reader=reader)
+        status, payload = self._get("/provenance?owner=didericis&repo=bot-bottle&issue=17")
+        self.assertEqual(200, status)
+        self.assertEqual("impl-17", payload["slug"])
+        self.assertEqual(1, len(payload["ops"]))  # type: ignore[arg-type]
+
+    def test_provenance_missing_params_400(self):
+        self._serve()
+        with self.assertRaises(HTTPError) as ctx:
+            self._get("/provenance?owner=didericis")
+        self.assertEqual(400, ctx.exception.code)
+
+    def test_provenance_unknown_run_404(self):
+        self._serve()
+        with self.assertRaises(HTTPError) as ctx:
+            self._get("/provenance?owner=x&repo=y&issue=1")
+        self.assertEqual(404, ctx.exception.code)
+
+
+if __name__ == "__main__":
+    unittest.main()