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_targeting.py

@@ -0,0 +1,60 @@
+"""Unit: targeting (labels + org membership)."""
+
+from __future__ import annotations
+
+import unittest
+
+from bot_bottle.orchestrator.model import IssueAssigned
+from bot_bottle.orchestrator.targeting import parse_labels, resolve_target
+
+from ._fakes import FakeForge
+
+
+def _issue(
+    assignees: tuple[str, ...] = ("agent-bot",),
+    labels: tuple[str, ...] = ("bot-bottle:implementer",),
+) -> IssueAssigned:
+    return IssueAssigned(
+        owner="didericis", repo="bot-bottle", issue_number=17,
+        title="t", body="b", assignees=tuple(assignees), labels=tuple(labels),
+    )
+
+
+class ParseLabelsTest(unittest.TestCase):
+    def test_agent_label(self):
+        self.assertEqual(("implementer", None), parse_labels(("bot-bottle:implementer",)))
+
+    def test_bottle_override_not_confused_with_agent(self):
+        agent, bottle = parse_labels(("bot-bottle:impl", "bot-bottle-bottle:dev"))
+        self.assertEqual(("impl", "dev"), (agent, bottle))
+
+    def test_no_agent_label(self):
+        self.assertEqual((None, None), parse_labels(("bug", "p1")))
+
+
+class ResolveTargetTest(unittest.TestCase):
+    def setUp(self):
+        self.forge = FakeForge(members=("agent-bot",))
+
+    def test_targeted(self):
+        target = resolve_target(_issue(), self.forge, "bot-bottle")
+        assert target is not None
+        self.assertEqual("implementer", target.agent_name)
+        self.assertIsNone(target.bottle_override)
+
+    def test_bottle_override(self):
+        ev = _issue(labels=("bot-bottle:impl", "bot-bottle-bottle:dev"))
+        target = resolve_target(ev, self.forge, "bot-bottle")
+        assert target is not None
+        self.assertEqual("dev", target.bottle_override)
+
+    def test_no_label_not_targeted(self):
+        self.assertIsNone(resolve_target(_issue(labels=("bug",)), self.forge, "bot-bottle"))
+
+    def test_non_member_assignee_not_targeted(self):
+        ev = _issue(assignees=("random-user",))
+        self.assertIsNone(resolve_target(ev, self.forge, "bot-bottle"))
+
+
+if __name__ == "__main__":
+    unittest.main()