spa hardening, offline logging, rate limit fixes

server:
- backup exporter, auth extractors, error shapes, CONTEXT (prior work)
- spa assets served outside the rate limit via route_layer
- requests_per_second went to per_second(), which takes an interval not a
  rate: 50 meant one request per 50s once burst was spent. now converted
  properly. 15/s, burst 60

spa fixes:
- account delete cleared snake_case token keys that were never written
- refresh interceptor could retry forever
- date ranges used local day boundaries stamped +00:00
- "all" period trend plotted one page; calendar days fabricated mood 3
- chart grid invisible: hsl(var(--border)) against rgba tokens
- blob url leak, orphaned media on failed save, devtools in prod bundle
- pt-safe/safe-area-pb classes never existed

spa features:
- offline outbox: entries queue to IndexedDB, replay with backoff, only
  server refusals count against an entry
- drafts persist, quick-log sheet, diary infinite scroll + filters
- route error boundary, stale-chunk recovery, no service worker in dev

a11y + perf:
- mood picker is a radiogroup, activity picker keyboard-operable,
  text alternatives for colour/emoji, locale week start
- dark glass over the bright photo: worst case 1.4:1 -> 4.9-9.6:1
- initial payload 1095->769kB raw, 306->230kB gzip; 38 unused components
  and 5 deps dropped; fonts 218->133kB

53 tests added (43 spa, 10 server)

spa/tests/lib/trend-buckets.test.ts

@@ -0,0 +1,51 @@
+import { describe, expect, it } from "vitest"
+import { aggregateTrend, bucketFor } from "@/lib/trend-buckets"
+import type { TrendPoint } from "@/hooks/use-trend"
+
+function day(date: string, mood: number, entryCount = 1): TrendPoint {
+  return { date, mood, entryCount }
+}
+
+describe("trend buckets", () => {
+  it("plots a day at a time over a week or a month", () => {
+    expect(bucketFor("week", 7)).toBe("day")
+    expect(bucketFor("month", 30)).toBe("day")
+  })
+
+  it("widens to weeks for a year and months beyond one", () => {
+    expect(bucketFor("year", 300)).toBe("week")
+    expect(bucketFor("all", 900)).toBe("month")
+  })
+
+  it("averages the days inside a bucket", () => {
+    const bars = aggregateTrend(
+      [day("2026-03-01", 2), day("2026-03-15", 4)],
+      "month"
+    )
+
+    expect(bars).toHaveLength(1)
+    expect(bars[0].average).toBe(3)
+  })
+
+  it("sums the entries behind a bucket, not the days", () => {
+    const bars = aggregateTrend(
+      [day("2026-03-01", 2, 3), day("2026-03-15", 4, 2)],
+      "month"
+    )
+
+    expect(bars[0].entryCount).toBe(5)
+  })
+
+  it("orders buckets oldest first", () => {
+    const bars = aggregateTrend(
+      [day("2026-05-02", 3), day("2026-01-02", 5), day("2026-03-02", 1)],
+      "month"
+    )
+
+    expect(bars.map((bar) => bar.average)).toEqual([5, 1, 3])
+  })
+
+  it("has nothing to plot for no days", () => {
+    expect(aggregateTrend([], "day")).toEqual([])
+  })
+})