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/e2e/gui-tools-essential.spec.ts

@@ -256,7 +256,14 @@ test.describe("GUI Essential Tools", () => {
     }) => {
       await page.goto("/crop");
 
-      const portraitPath = path.join(process.cwd(), "tests", "fixtures", "test-portrait-tall.png");
+      const portraitPath = path.join(
+        process.cwd(),
+        "tests",
+        "fixtures",
+        "image",
+        "edge",
+        "test-portrait-tall.png",
+      );
       const fileChooserPromise = page.waitForEvent("filechooser");
       await page.locator("[class*='border-dashed']").first().click();
       const fileChooser = await fileChooserPromise;