fix(12.2): close code-review blockers on uploads, JSON caps, and pivot fill

Keep form save behind in-flight uploads, make retries idempotent via X-Upload-Id, cap remaining JSON bodies, and surface pending pivot type errors instead of zeroing them.

Co-authored-by: Cursor <cursoragent@cursor.com>

admin/tests/app/dateFormat.test.ts

@@ -196,7 +196,25 @@ describe('dayBounds and boundValue', () => {
     expect(boundValue(day, 'datetime', true, true)?.toString()).toBe('2026-10-02T23:59:59')
     const zoned = boundValue(day, 'datetime', false, false) as ZonedDateTime
     expect(zoned.timeZone).toBe('Europe/Warsaw')
-    expect([zoned.hour, zoned.minute]).toEqual([0, 0])
+    // UTC 2026-10-02 00:00 is 02:00 in Warsaw (CEST).
+    expect([zoned.hour, zoned.minute]).toEqual([2, 0])
+    const max = boundValue(day, 'datetime', false, true) as ZonedDateTime
+    expect([max.hour, max.minute, max.second]).toEqual([1, 59, 59])
+    expect(max.day).toBe(3)
+  })
+
+  it('uses UTC-day instants so a local midnight just after the UTC date change is out of range', () => {
+    const min = boundValue(new CalendarDate(2000, 1, 1), 'datetime', false, false) as ZonedDateTime
+    const local = parseFieldValue('datetime', '2000-01-01T00:30:00+01:00') as ZonedDateTime
+    expect(local.compare(min)).toBeLessThan(0)
+    const allowed = parseFieldValue('datetime', '2000-01-01T01:30:00+01:00') as ZonedDateTime
+    expect(allowed.compare(min)).toBeGreaterThanOrEqual(0)
+    setLocalTimeZone('America/New_York')
+    const max = boundValue(new CalendarDate(2000, 1, 1), 'datetime', false, true) as ZonedDateTime
+    const evening = parseFieldValue('datetime', '2000-01-01T20:00:00-05:00') as ZonedDateTime
+    expect(evening.compare(max)).toBeGreaterThan(0)
+    const afternoon = parseFieldValue('datetime', '2000-01-01T15:00:00-05:00') as ZonedDateTime
+    expect(afternoon.compare(max)).toBeLessThanOrEqual(0)
   })
 
   it('starts a fresh picker at today in its value type', () => {