test: reorganize fixture files into modality-first layout (phase 6b)

Move all fixture files from flat/mixed dirs (content/, media/, documents/,
formats/, hostile/, root loose) into the modality-first hierarchy:
image/{valid,formats,edge,hostile}, video/{valid,formats,hostile},
audio/{valid,formats,hostile}, document/{valid,formats,edge,hostile},
data/valid/, security/. Update index.ts paths, fixtureDir aliases,
all literal refs in 17 e2e/qa/script files, manifest.json, and the
three generator scripts. 163 files moved, 0 dropped, 100 new tests
from expanded document scan.

tests/fixtures/image/.gitkeep

@@ -1 +0,0 @@
-Phase 6 reorg moves image fixtures here (valid/ formats/ edge/ hostile/). See ../README.md.

tests/fixtures/image/edge/test-image-urls.txt

@@ -0,0 +1,30 @@
+https://picsum.photos/id/10/800/600
+https://picsum.photos/id/20/1024/768
+https://picsum.photos/id/37/800/600
+https://picsum.photos/id/42/640/480
+https://picsum.photos/id/55/1280/720
+https://picsum.photos/id/100/800/800
+https://picsum.photos/id/119/500/500
+https://picsum.photos/id/137/1920/1080
+https://picsum.photos/id/160/600/400
+https://picsum.photos/id/180/300/300
+https://picsum.photos/id/200/800/600
+https://picsum.photos/id/237/400/300
+https://picsum.photos/id/256/1024/768
+https://picsum.photos/id/292/800/600
+https://picsum.photos/id/338/640/480
+https://picsum.photos/id/366/1280/720
+https://picsum.photos/id/399/800/800
+https://picsum.photos/id/433/500/500
+https://picsum.photos/id/501/1920/1080
+https://picsum.photos/id/550/600/400
+https://picsum.photos/seed/snapotter1/800/600
+https://picsum.photos/seed/snapotter2/1024/768
+https://picsum.photos/seed/snapotter3/640/480
+https://picsum.photos/id/670/800/600?grayscale
+https://picsum.photos/id/700/1024/768?blur=2
+https://picsum.photos/id/870/800/600?grayscale&blur=2
+https://picsum.photos/id/1002/400/400
+https://picsum.photos/id/1015/800/600
+https://picsum.photos/id/1025/1280/720
+https://picsum.photos/id/1043/1920/1080

tests/fixtures/image/valid/qr-code.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="296" height="296" viewBox="0 0 29 29" shape-rendering="crispEdges"><path fill="#ffffff" d="M0 0h29v29H0z"/><path stroke="#000000" d="M2 2.5h7m1 0h1m3 0h1m1 0h1m1 0h1m1 0h7M2 3.5h1m5 0h1m1 0h2m1 0h2m5 0h1m5 0h1M2 4.5h1m1 0h3m1 0h1m1 0h2m2 0h2m2 0h1m1 0h1m1 0h3m1 0h1M2 5.5h1m1 0h3m1 0h1m4 0h1m1 0h1m4 0h1m1 0h3m1 0h1M2 6.5h1m1 0h3m1 0h1m1 0h1m1 0h2m2 0h1m1 0h1m1 0h1m1 0h3m1 0h1M2 7.5h1m5 0h1m2 0h2m1 0h2m4 0h1m5 0h1M2 8.5h7m1 0h1m1 0h1m1 0h1m1 0h1m1 0h1m1 0h7M12 9.5h4m2 0h1M2 10.5h1m2 0h6m1 0h1m1 0h1m1 0h4m2 0h1m1 0h3M2 11.5h1m2 0h2m2 0h3m2 0h4m3 0h5M2 12.5h1m1 0h1m1 0h1m1 0h3m2 0h1m1 0h1m1 0h1m3 0h1m1 0h1m2 0h1M2 13.5h1m6 0h1m1 0h1m1 0h1m2 0h1m2 0h1m3 0h4M2 14.5h2m1 0h4m1 0h1m1 0h1m1 0h1m2 0h1m2 0h1m5 0h1M2 15.5h1m1 0h2m1 0h1m2 0h1m5 0h3m3 0h1m2 0h1M2 16.5h9m2 0h6m1 0h1m1 0h5M2 17.5h1m1 0h3m2 0h1m2 0h2m5 0h3m1 0h2m1 0h1M2 18.5h1m5 0h1m7 0h7m1 0h2M10 19.5h6m1 0h2m3 0h1m1 0h2M2 20.5h7m1 0h1m1 0h2m4 0h1m1 0h1m1 0h1m3 0h1M2 21.5h1m5 0h1m1 0h1m1 0h1m1 0h1m1 0h3m3 0h1m2 0h2M2 22.5h1m1 0h3m1 0h1m1 0h1m3 0h9m2 0h2M2 23.5h1m1 0h3m1 0h1m1 0h2m4 0h2m1 0h2m4 0h2M2 24.5h1m1 0h3m1 0h1m3 0h1m1 0h1m1 0h1m1 0h1m3 0h5M2 25.5h1m5 0h1m2 0h1m4 0h1m2 0h4m1 0h3M2 26.5h7m1 0h1m1 0h1m2 0h2m1 0h3m2 0h1m2 0h1"/></svg>

tests/fixtures/image/valid/svg-logo.svg

@@ -0,0 +1,24 @@
+<svg width="400" height="400" viewBox="0 0 400 400" fill="none" xmlns="http://www.w3.org/2000/svg">
+  <title>SnapOtter Test Fixture</title>
+  <desc>CC0 geometric test SVG generated by gen-synthetic-content.mjs</desc>
+  <defs>
+    <linearGradient id="bg" x1="0" y1="0" x2="400" y2="400">
+      <stop stop-color="#E07832"/>
+      <stop offset="1" stop-color="#C06520"/>
+    </linearGradient>
+    <filter id="glow" x="-20%" y="-20%" width="140%" height="140%">
+      <feGaussianBlur in="SourceGraphic" stdDeviation="4" result="blur"/>
+      <feMerge><feMergeNode in="blur"/><feMergeNode in="SourceGraphic"/></feMerge>
+    </filter>
+  </defs>
+  <rect width="400" height="400" fill="#1a1210"/>
+  <circle cx="200" cy="180" r="100" fill="url(#bg)" filter="url(#glow)"/>
+  <ellipse cx="200" cy="180" rx="60" ry="40" fill="#1a1210" opacity="0.3"/>
+  <circle cx="170" cy="160" r="12" fill="white"/>
+  <circle cx="230" cy="160" r="12" fill="white"/>
+  <circle cx="170" cy="160" r="5" fill="#1a1210"/>
+  <circle cx="230" cy="160" r="5" fill="#1a1210"/>
+  <ellipse cx="200" cy="195" rx="15" ry="8" fill="#1a1210" opacity="0.4"/>
+  <text x="200" y="320" font-family="Helvetica, Arial, sans-serif" font-size="28" font-weight="bold" text-anchor="middle" fill="#F0EBE4">TEST FIXTURE</text>
+  <text x="200" y="350" font-family="Helvetica, Arial, sans-serif" font-size="14" text-anchor="middle" fill="#6B6560">CC0 - Generated Asset</text>
+</svg>

tests/fixtures/image/valid/test-100x100.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100" viewBox="0 0 100 100">
+  <rect width="100" height="100" fill="#4a90d9"/>
+  <circle cx="50" cy="50" r="30" fill="#ffffff"/>
+</svg>