refactor(tools): bin/{subject}/{method} layout; Go serve+watch modules

Move serve/ (module) -> bin/server, tools/ -> bin/tools, replace bin/kb-watch
bash with bin/watch Go package; self-executing Go shebangs bin/serve.go and
bin/kb/watch.go; Docker + CI + git/import + docs repointed. Multi-stage image
builds static serve+watch binaries (no Go runtime in container).

bin/tools/test_gitgraph.py

@@ -0,0 +1,71 @@
+import os
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent))
+
+import kblib  # noqa: E402
+import gitimport  # noqa: E402
+
+SAMPLE = (
+    "\x1e" + "a1b2c3d" + "\x1f" + "Ada Lovelace" + "\x1f" + "ada@example.com"
+    + "\x1f" + "2026-08-10T12:00:00+01:00" + "\x1f" + "feat: first commit"
+    + "\n\nREADME.md\nsrc/main.c\n"
+)
+
+COMMIT_PERSON_SCHEMA = (
+    "CREATE NODE TABLE IF NOT EXISTS Commit (id STRING, repo STRING, subject STRING, "
+    "author STRING, email STRING, date STRING, PRIMARY KEY(id))"
+)
+PERSON_SCHEMA = (
+    "CREATE NODE TABLE IF NOT EXISTS Person (id STRING, name STRING, email STRING, PRIMARY KEY(id))"
+)
+HAS_VERSION_SCHEMA = "CREATE REL TABLE IF NOT EXISTS HAS_VERSION (FROM File TO Commit)"
+AUTHORED_SCHEMA = "CREATE REL TABLE IF NOT EXISTS AUTHORED (FROM Commit TO Person)"
+
+
+class GitGraphTest(unittest.TestCase):
+    def setUp(self):
+        self.dir = tempfile.mkdtemp()
+        self.dbpath = os.path.join(self.dir, "kb.lbug")
+        self.db, self.conn = kblib.connect(self.dbpath, read_only=False)
+        kblib.init_schema(self.conn)
+        self.conn.execute(COMMIT_PERSON_SCHEMA)
+        self.conn.execute(PERSON_SCHEMA)
+        self.conn.execute(HAS_VERSION_SCHEMA)
+        self.conn.execute(AUTHORED_SCHEMA)
+
+    def tearDown(self):
+        self.conn.close()
+        self.db.close()
+
+    def test_index_commits_creates_nodes_and_edges(self):
+        cs = gitimport.parse_log(SAMPLE)
+        gitimport.index_commits(self.conn, cs, "sample-repo")
+        rp = self.conn.execute("MATCH (p:Person) RETURN p.name, p.email").get_all()
+        self.assertEqual([tuple(r) for r in rp], [("Ada Lovelace", "ada@example.com")])
+        rc = self.conn.execute("MATCH (c:Commit) RETURN c.id, c.repo").get_all()
+        self.assertEqual(len(rc), 1)
+        self.assertEqual(rc[0][1], "sample-repo")
+        # File -[:HAS_VERSION]-> Commit -[:AUTHORED]-> Person
+        rf = self.conn.execute(
+            "MATCH (f:File)-[:HAS_VERSION]->(c:Commit)-[:AUTHORED]->(p:Person) "
+            "RETURN f.path, c.id, p.email").get_all()
+        paths = sorted(r[0] for r in rf)
+        self.assertEqual(paths, ["README.md", "src/main.c"])
+        self.assertTrue(all(r[2] == "ada@example.com" for r in rf))
+
+    def test_index_commits_idempotent(self):
+        cs = gitimport.parse_log(SAMPLE)
+        gitimport.index_commits(self.conn, cs, "sample-repo")
+        gitimport.index_commits(self.conn, cs, "sample-repo")
+        n = self.conn.execute("MATCH (c:Commit) RETURN count(*)").get_all()[0][0]
+        self.assertEqual(n, 1)
+        p = self.conn.execute("MATCH (p:Person) RETURN count(*)").get_all()[0][0]
+        self.assertEqual(p, 1)
+
+
+if __name__ == "__main__":
+    unittest.main()