test: cover _daemon_reachable timeout path and DbStore.is_migrated

Two diff-coverage gaps on the ci-kvm-runner branch:

1. bot_bottle/backend/docker/setup.py: the try/except TimeoutExpired
   block added in a prior commit had no tests reaching the subprocess
   path. Add two tests to TestDockerSetupStatus: one for the success
   path (subprocess returns 0) and one for the TimeoutExpired fallback.

2. bot_bottle/db_store.py: the _connection() context manager change in
   is_migrated() was never exercised by unit tests (all callers mock
   is_migrated() directly). Add test_db_store.py covering the absent-DB,
   missing-schema-table, migrated, and behind-schema cases.

tests/unit/test_backend_setup.py

@@ -215,6 +215,18 @@ class TestDockerSetupStatus(unittest.TestCase):
         with patch.object(dk.shutil, "which", return_value=None):
             self.assertFalse(dk._daemon_reachable())
 
+    def test_daemon_reachable_true_when_daemon_responds(self):
+        with patch.object(dk.shutil, "which", return_value="/usr/bin/docker"), \
+             patch.object(dk.subprocess, "run",
+                          return_value=subprocess.CompletedProcess([], 0)):
+            self.assertTrue(dk._daemon_reachable())
+
+    def test_daemon_reachable_false_on_timeout(self):
+        with patch.object(dk.shutil, "which", return_value="/usr/bin/docker"), \
+             patch.object(dk.subprocess, "run",
+                          side_effect=subprocess.TimeoutExpired(["docker", "info"], 5)):
+            self.assertFalse(dk._daemon_reachable())
+
     def test_status_reports_missing_docker(self):
         with patch.object(dk.shutil, "which", return_value=None):
             rc, out = _cap(dk.status)

tests/unit/test_db_store.py

@@ -0,0 +1,58 @@
+"""Unit: DbStore._connection() context manager and is_migrated()."""
+
+from __future__ import annotations
+
+import sqlite3
+import tempfile
+import unittest
+from pathlib import Path
+
+from bot_bottle.db_store import DbStore
+from bot_bottle.migrations import TableMigrations
+
+
+def _store(tmp: Path) -> DbStore:
+    migrations = TableMigrations("test", ["CREATE TABLE items (id INTEGER PRIMARY KEY)"])
+    return DbStore(tmp / "test.db", migrations)
+
+
+class TestDbStoreIsMigrated(unittest.TestCase):
+    def test_returns_false_when_db_absent(self):
+        with tempfile.TemporaryDirectory() as d:
+            store = _store(Path(d))
+            self.assertFalse(store.is_migrated())
+
+    def test_returns_false_when_schema_versions_missing(self):
+        # DB file exists but has no schema_versions table → OperationalError → False.
+        with tempfile.TemporaryDirectory() as d:
+            store = _store(Path(d))
+            conn = sqlite3.connect(store.db_path)
+            conn.close()
+            self.assertFalse(store.is_migrated())
+
+    def test_returns_true_after_migrate(self):
+        with tempfile.TemporaryDirectory() as d:
+            store = _store(Path(d))
+            store.migrate()
+            self.assertTrue(store.is_migrated())
+
+    def test_returns_false_when_behind(self):
+        with tempfile.TemporaryDirectory() as d:
+            migrations = TableMigrations(
+                "test",
+                [
+                    "CREATE TABLE items (id INTEGER PRIMARY KEY)",
+                    "ALTER TABLE items ADD COLUMN name TEXT",
+                ],
+            )
+            store = DbStore(Path(d) / "test.db", migrations)
+            # Apply only the first migration manually.
+            conn = sqlite3.connect(store.db_path)
+            with conn:
+                TableMigrations("test", [migrations.migrations[0]]).apply(conn)
+            conn.close()
+            self.assertFalse(store.is_migrated())
+
+
+if __name__ == "__main__":
+    unittest.main()