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/activity-groups.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, it } from "vitest"
+import { UNCATEGORISED, groupByCategory } from "@/lib/activity-groups"
+
+const activity = (name: string, category: string | null) => ({ name, category })
+
+describe("grouping activities", () => {
+  it("sorts categories alphabetically", () => {
+    const groups = groupByCategory([
+      activity("run", "sport"),
+      activity("read", "hobby"),
+    ])
+
+    expect(groups.map((group) => group.category)).toEqual(["hobby", "sport"])
+  })
+
+  it("puts activities with no category last", () => {
+    const groups = groupByCategory([
+      activity("nap", null),
+      activity("run", "sport"),
+      activity("read", "hobby"),
+    ])
+
+    expect(groups.map((group) => group.category)).toEqual([
+      "hobby",
+      "sport",
+      UNCATEGORISED,
+    ])
+  })
+
+  it("keeps activities within a category in the order given", () => {
+    const groups = groupByCategory([
+      activity("run", "sport"),
+      activity("swim", "sport"),
+    ])
+
+    expect(groups[0].items.map((item) => item.name)).toEqual(["run", "swim"])
+  })
+
+  it("has no groups for no activities", () => {
+    expect(groupByCategory([])).toEqual([])
+  })
+})