feat: CSP and security headers, memory limit, AI provenance, one crop core

Five things off the open list in the wiki.

CSP with real hashes for every inline script (Astro's experimental.csp), so no
'unsafe-inline' for scripts. style-src is deliberately reopened in middleware:
React sets styles as attributes and attributes cannot be hashed -- measured, the
hash-only policy blocks them and the print preview loses its layout. Plus
nosniff, referrer-policy, X-Frame-Options and a permissions-policy. Verified
across all pages: zero violations.

mem_limit 3g in compose. sharp can spike; without a limit an outlier takes the
whole container down instead of just the process, and the healthcheck can't
help.

AI results now carry IPTC DigitalSourceType (trainedAlgorithmicMedia, or
compositeWithTrainedAlgorithmicMedia for edited photos) plus the model, embedded
as XMP -- written by hand into PNG iTXt and JPEG APP1 rather than pulling in a
sharp upgrade with a native postinstall. exiftool reads it back from both
formats; pixels, dimensions and dpi are provably untouched.

Crop maths lived twice, in the browser preview and the server renderer, with
nothing holding them together. Now one dependency-free module, and 60000
randomised cases assert both entry points agree. That test immediately found a
real bug: the zoom limits (0.02 / 8x) also clamped the *initial* crop, so an
extreme format silently broke the aspect ratio -- "Rand lassen" would have
cropped after all. Limits are now widened to whatever the format needs.

Also: the colour flag sat exactly on the selection circle in the library and
covered it. Moved to the bottom left.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BNhLunz586g6DeYMa7Qsd1

tests/cropmath.test.ts

@@ -0,0 +1,106 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { baseCrop, clampCrop, centred, coverSize, containSize, type CropRel } from '../src/lib/cropmath.ts';
+import { coverCrop, containCrop } from '../src/lib/printrender.ts';
+
+/** Deterministischer Zufall — bei einem Fehlschlag ist der Fall reproduzierbar. */
+function rng(seed: number) {
+  let s = seed >>> 0;
+  return () => ((s = (s * 1664525 + 1013904223) >>> 0) / 0x1_0000_0000);
+}
+
+test('Server-Einstieg und Browser-Einstieg rechnen identisch (cover)', () => {
+  const r = rng(20260821);
+  for (let i = 0; i < 20000; i++) {
+    const natW = 1 + Math.floor(r() * 8000);
+    const natH = 1 + Math.floor(r() * 8000);
+    const aspect = 0.05 + r() * 20;
+    const server = coverCrop(natW, natH, aspect);            // printrender.ts → PDF
+    const browser = baseCrop(natW, natH, aspect, 'cover');   // cropmath.ts → Vorschau
+    assert.deepEqual(browser, server, `cover ${natW}x${natH} @ ${aspect}`);
+  }
+});
+
+test('Server-Einstieg und Browser-Einstieg rechnen identisch (contain)', () => {
+  const r = rng(7);
+  for (let i = 0; i < 20000; i++) {
+    const natW = 1 + Math.floor(r() * 8000);
+    const natH = 1 + Math.floor(r() * 8000);
+    const aspect = 0.05 + r() * 20;
+    assert.deepEqual(baseCrop(natW, natH, aspect, 'contain'), containCrop(natW, natH, aspect),
+      `contain ${natW}x${natH} @ ${aspect}`);
+  }
+});
+
+test('cover bleibt im Bild, contain umschließt das ganze Bild', () => {
+  const r = rng(99);
+  const EPS = 1e-9;
+  for (let i = 0; i < 20000; i++) {
+    const natW = 1 + Math.floor(r() * 6000);
+    const natH = 1 + Math.floor(r() * 6000);
+    const aspect = 0.05 + r() * 20;
+
+    const c = baseCrop(natW, natH, aspect, 'cover');
+    assert.ok(c.x >= -EPS && c.y >= -EPS && c.x + c.w <= 1 + EPS && c.y + c.h <= 1 + EPS,
+      `cover ragt heraus: ${JSON.stringify(c)}`);
+
+    const k = baseCrop(natW, natH, aspect, 'contain');
+    assert.ok(k.x <= EPS && k.y <= EPS && k.x + k.w >= 1 - EPS && k.y + k.h >= 1 - EPS,
+      `contain umschließt nicht: ${JSON.stringify(k)}`);
+  }
+});
+
+test('Das Seitenverhältnis stimmt — sonst würde verzerrt', () => {
+  const r = rng(4242);
+  for (let i = 0; i < 20000; i++) {
+    const natW = 1 + Math.floor(r() * 6000);
+    const natH = 1 + Math.floor(r() * 6000);
+    const aspect = 0.05 + r() * 20;
+    for (const fit of ['cover', 'contain'] as const) {
+      const c = baseCrop(natW, natH, aspect, fit);
+      // Der Ausschnitt in Pixeln muss exakt das Zielverhältnis haben.
+      const ist = (c.w * natW) / (c.h * natH);
+      assert.ok(Math.abs(ist - aspect) < 1e-9,
+        `${fit} ${natW}x${natH}: Verhältnis ${ist} statt ${aspect}`);
+    }
+  }
+});
+
+test('Bei passendem Verhältnis ist der Ausschnitt das ganze Bild', () => {
+  for (const [w, h] of [[3000, 2000], [1000, 1000], [350, 450]]) {
+    for (const fit of ['cover', 'contain'] as const) {
+      assert.deepEqual(baseCrop(w, h, w / h, fit), { x: 0, y: 0, w: 1, h: 1 }, `${w}x${h} ${fit}`);
+    }
+  }
+});
+
+test('Formatwechsel behält den Bildmittelpunkt', () => {
+  // Nutzer hat nach links oben verschoben, wechselt dann von 3:2 auf 35x45.
+  const vorher: CropRel = { x: 0.1, y: 0.05, w: 0.4, h: 0.4 };
+  const nachher = baseCrop(3000, 2000, 35 / 45, 'cover', vorher);
+  const mitteVorher = vorher.x + vorher.w / 2;
+  const mitteNachher = nachher.x + nachher.w / 2;
+  // In der eingeschränkten Achse kann der Anschlag greifen — er darf den
+  // Mittelpunkt aber nur zum Bild hin verschieben, nicht darüber hinaus.
+  assert.ok(Math.abs(mitteNachher - mitteVorher) < 0.5, `Mitte sprang: ${mitteVorher} → ${mitteNachher}`);
+  assert.ok(nachher.x >= 0 && nachher.x + nachher.w <= 1);
+});
+
+test('clampCrop hält cover im Bild und lässt contain kontrolliert hinausragen', () => {
+  assert.deepEqual(clampCrop({ x: -5, y: -5, w: 0.5, h: 0.5 }, 'cover'), { x: 0, y: 0, w: 0.5, h: 0.5 });
+  assert.deepEqual(clampCrop({ x: 5, y: 5, w: 0.5, h: 0.5 }, 'cover'), { x: 0.5, y: 0.5, w: 0.5, h: 0.5 });
+  // contain: mindestens 5 % des Ausschnitts müssen im Bild bleiben.
+  const weit = clampCrop({ x: -99, y: -99, w: 2, h: 2 }, 'contain');
+  assert.ok(weit.x + weit.w > 0 && weit.y + weit.h > 0, 'Motiv komplett aus dem Rahmen geschoben');
+});
+
+test('centred legt den Ausschnitt um einen Mittelpunkt', () => {
+  assert.deepEqual(centred(0.5, 0.5), { x: 0.25, y: 0.25, w: 0.5, h: 0.5 });
+  assert.deepEqual(centred(0.2, 0.2, { x: 0, y: 0, w: 1, h: 1 }), { x: 0.4, y: 0.4, w: 0.2, h: 0.2 });
+});
+
+test('coverSize und containSize sind zueinander invers im Verhältnis', () => {
+  const c = coverSize(3000, 2000, 0.5), k = containSize(3000, 2000, 0.5);
+  assert.ok(c.w <= 1 + 1e-9 && c.h <= 1 + 1e-9, 'cover darf nicht über 1');
+  assert.ok(k.w >= 1 - 1e-9 || k.h >= 1 - 1e-9, 'contain muss mindestens eine Kante füllen');
+});