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/instant-range.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, it } from "vitest"
+import { rangeOfDays, rangeOfMonth, rangeOfYear } from "@/lib/instant-range"
+
+const OFFSET = /[+-]\d{2}:\d{2}$/
+
+describe("instant ranges", () => {
+  it("carries the reader's own offset rather than assuming UTC", () => {
+    const { from, to } = rangeOfMonth(new Date(2026, 7, 15))
+
+    expect(from).toMatch(OFFSET)
+    expect(to).toMatch(OFFSET)
+  })
+
+  it("starts a month at local midnight on the first", () => {
+    const { from } = rangeOfMonth(new Date(2026, 7, 15))
+
+    expect(from.startsWith("2026-08-01T00:00:00")).toBe(true)
+  })
+
+  it("ends a month on the last day, not the first of the next", () => {
+    const { to } = rangeOfMonth(new Date(2026, 7, 15))
+
+    expect(to.startsWith("2026-08-31T23:59:59")).toBe(true)
+  })
+
+  it("covers a whole year", () => {
+    const { from, to } = rangeOfYear(2025)
+
+    expect(from.startsWith("2025-01-01T00:00:00")).toBe(true)
+    expect(to.startsWith("2025-12-31T23:59:59")).toBe(true)
+  })
+
+  it("widens a span to whole days at both ends", () => {
+    const { from, to } = rangeOfDays(
+      new Date(2026, 0, 5, 13, 30),
+      new Date(2026, 0, 7, 9, 15)
+    )
+
+    expect(from.startsWith("2026-01-05T00:00:00")).toBe(true)
+    expect(to.startsWith("2026-01-07T23:59:59")).toBe(true)
+  })
+})