initial: toy notes service used to demo pragent

A deliberately small Python service — auth helpers, a sqlite-backed store, and
two request handlers — plus a .pr-review.json that steers the reviewer toward
this repo's house rules. Pull requests against it carry planted defects so the
reviewer has something real to find.

tests/test_store.py

@@ -0,0 +1,21 @@
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from app.store import Store  # noqa: E402
+
+
+def test_add_and_get_note():
+    s = Store()
+    nid = s.add_note("alice", "hello", "world")
+    note = s.get_note(nid)
+    assert note[1] == "alice"
+    assert note[2] == "hello"
+
+
+def test_notes_are_scoped_to_owner():
+    s = Store()
+    s.add_note("alice", "a", "1")
+    s.add_note("bob", "b", "2")
+    assert len(s.notes_for("alice")) == 1