fix(labs): strict numeric parsing, atomic confirm guard, test integrity

- normalize.ts num(): parseFloat truncated at the first comma, so "1,200"
  silently became 1 (1000x error) and "5,5" became 5. Now strictly matches
  either US thousands-grouping or a plain number spanning the whole string;
  anything else (incl. ambiguous "5,5") returns null instead of a wrong value.
- labs.ts confirm handler: the pending-status check ran before the request
  body was read, so two concurrent confirms could both pass it and
  double-insert. Added a guarded UPDATE ... WHERE status = 'pending' as the
  first statement inside the existing synchronous transaction; zero rows
  affected throws and the route returns 409, with the fast-path check kept
  for the common case.
- Added missing `await` on two rejects.toThrow assertions (llm.test.ts,
  extract.test.ts) that were previously resolving before the assertion
  settled.
- Bumped the 11th-failed-login rate-limit test to a 30s timeout — 10
  sequential argon2id verifies can exceed bun:test's 5s default under load.

server/test/labs-confirm.test.ts

@@ -64,6 +64,13 @@ describe("draft review", () => {
       body: JSON.stringify({ collectedDate: "2026-01-15", labName: null, markers: [{ panel: null, name: "X", value: "1", unit: null, referenceRange: null, flagged: false }] }),
     });
     expect(again.status).toBe(409);
+
+    // Second (rejected) confirm must not have inserted a second draw or any
+    // extra biomarker rows — exactly one draw, one set of biomarkers.
+    const drawsAfter = await db.select().from(labDraws);
+    expect(drawsAfter).toHaveLength(1);
+    const rowsAfter = await db.select().from(biomarkers);
+    expect(rowsAfter).toHaveLength(2);
   });
 
   test("discard marks draft discarded", async () => {