feat(shared): add Section concept and toolSection() partition

tests/unit/shared/section.test.ts

@@ -0,0 +1,37 @@
+import { SECTIONS, type Section, TOOLS, toolSection } from "@snapotter/shared";
+import { describe, expect, it } from "vitest";
+
+describe("toolSection", () => {
+  it("maps non-document modalities directly", () => {
+    expect(toolSection({ modality: "image", acceptedInputs: [".png"] })).toBe("image");
+    expect(toolSection({ modality: "video", acceptedInputs: [".mp4"] })).toBe("video");
+    expect(toolSection({ modality: "audio", acceptedInputs: [".mp3"] })).toBe("audio");
+    expect(toolSection({ modality: "file", acceptedInputs: [".csv"] })).toBe("files");
+  });
+
+  it("splits document modality by .pdf input", () => {
+    expect(toolSection({ modality: "document", acceptedInputs: [".pdf"] })).toBe("pdf");
+    expect(toolSection({ modality: "document", acceptedInputs: [".docx", ".odt"] })).toBe("files");
+  });
+
+  it("partitions the catalog into exactly 25 PDF and 22 Files tools", () => {
+    const bySection = (s: Section) =>
+      TOOLS.filter((t) => toolSection(t) === s)
+        .map((t) => t.id)
+        .sort();
+    expect(TOOLS.filter((t) => toolSection(t) === "image")).toHaveLength(64);
+    expect(TOOLS.filter((t) => toolSection(t) === "video")).toHaveLength(29);
+    expect(TOOLS.filter((t) => toolSection(t) === "audio")).toHaveLength(17);
+    expect(bySection("pdf")).toHaveLength(25);
+    expect(bySection("files")).toHaveLength(22);
+    expect(bySection("pdf")).toContain("merge-pdf");
+    expect(bySection("pdf")).toContain("ocr-pdf");
+    expect(bySection("files")).toContain("word-to-pdf");
+    expect(bySection("files")).toContain("convert-spreadsheet");
+    expect(bySection("files")).toContain("csv-json");
+  });
+
+  it("exposes 5 ordered sections", () => {
+    expect(SECTIONS.map((s) => s.id)).toEqual(["image", "video", "audio", "pdf", "files"]);
+  });
+});