fix: update tool count to 52 and add ai-canvas-expand to landing page

ai-canvas-expand was added to constants.ts and route files but never
added to the landing page bento grid, causing all hardcoded counts
to remain at 51. This updates all references across source, docs,
i18n, and tests to reflect the correct count of 52 tools.

tests/e2e-docs/homepage.spec.ts

@@ -13,7 +13,7 @@ test.describe("Docs Homepage", () => {
     await expect(page.getByText("SnapOtter").first()).toBeVisible();
     await expect(page.getByText("A Self Hosted Image Manipulator")).toBeVisible();
     await expect(
-      page.getByText("51 tools. Local AI. No cloud. Your images never leave your home."),
+      page.getByText("52 tools. Local AI. No cloud. Your images never leave your home."),
     ).toBeVisible();
   });
 
@@ -29,7 +29,7 @@ test.describe("Docs Homepage", () => {
 
   test("features section renders all 6 feature cards", async ({ page }) => {
     const features = [
-      "51 Image Tools",
+      "52 Image Tools",
       "Local AI",
       "Pipelines",
       "REST API",