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_store.py

@@ -0,0 +1,50 @@
+"""Unit: InMemoryStateStore."""
+
+from __future__ import annotations
+
+import unittest
+
+from bot_bottle.orchestrator.model import RunRecord
+from bot_bottle.orchestrator.store import InMemoryStateStore
+
+
+def _rec(issue: int, owner: str = "o") -> RunRecord:
+    return RunRecord(owner=owner, repo="r", issue_number=issue, slug=f"s{issue}",
+                     agent_name="a")
+
+
+class InMemoryStoreTest(unittest.TestCase):
+    def setUp(self):
+        self.store = InMemoryStateStore()
+
+    def test_upsert_get(self):
+        self.store.upsert(_rec(1))
+        got = self.store.get("o", "r", 1)
+        assert got is not None
+        self.assertEqual("s1", got.slug)
+
+    def test_get_missing(self):
+        self.assertIsNone(self.store.get("o", "r", 99))
+
+    def test_upsert_replaces(self):
+        self.store.upsert(_rec(1))
+        r = _rec(1)
+        r.slug = "changed"
+        self.store.upsert(r)
+        self.assertEqual("changed", self.store.get("o", "r", 1).slug)  # type: ignore[union-attr]
+        self.assertEqual(1, len(self.store.all()))
+
+    def test_delete(self):
+        self.store.upsert(_rec(1))
+        self.store.delete("o", "r", 1)
+        self.assertIsNone(self.store.get("o", "r", 1))
+
+    def test_all_sorted(self):
+        self.store.upsert(_rec(2, owner="b"))
+        self.store.upsert(_rec(1, owner="a"))
+        self.assertEqual([("a", 1), ("b", 2)],
+                         [(r.owner, r.issue_number) for r in self.store.all()])
+
+
+if __name__ == "__main__":
+    unittest.main()