PARTITION KEY support (#122)

* initial pass at PARTITION KEY support.

* unit tests

* gha this PR branch

* fixup tests

* doc internal

* fix tests, KNN/rowids in

* define SQLITE_INDEX_CONSTRAINT_OFFSET

* whoops

* update tests, syrupy, use uv

* un ignore pyproject.toml

* dot

* tests/

* type error?

* win: .exe, update error name

* try fix macos python, paren around expr?

* win bash?

* dbg :(

* explicit error

* op

* dbg win

* win ./tests/.venv/Scripts/python.exe

* block UPDATEs on partition key values for now

tests/skip.test-correctness.py

@@ -0,0 +1,49 @@
+import sqlite3
+import json
+
+db = sqlite3.connect("test2.db")
+db.enable_load_extension(True)
+db.load_extension("dist/vec0")
+db.enable_load_extension(False)
+db.row_factory = sqlite3.Row
+db.execute('attach database "sift1m-base.db" as sift1m')
+
+
+#def test_sift1m():
+rows = db.execute(
+  '''
+    with q as (
+      select rowid, vector, k100 from sift1m.sift1m_query limit 10
+    ),
+    results as (
+      select
+        q.rowid as query_rowid,
+        vec_sift1m.rowid as vec_rowid,
+        distance,
+        k100 as k100_groundtruth
+      from q
+      join vec_sift1m
+      where
+        vec_sift1m.vector match q.vector
+        and k = 100
+      order by distance
+    )
+    select
+      query_rowid,
+      json_group_array(vec_rowid order by distance) as topk,
+      k100_groundtruth,
+      json_group_array(vec_rowid order by distance) == k100_groundtruth
+    from results
+    group by 1;
+  ''').fetchall()
+
+results = []
+for row in rows:
+  actual = json.loads(row["topk"])
+  expected = json.loads(row["k100_groundtruth"])
+
+  ncorrect = sum([x in expected for x in actual])
+  results.append(ncorrect / 100.0)
+
+from statistics import mean
+print(mean(results))