feat(automate): make the pipeline builder fully multi-modal (#335)

* feat(shared): add outputModality to Tool metadata for crossing tools

* feat(shared): add modalityForExtension, toolInputModality, toolOutputModality

* fix(pipeline): route finalize and parent jobs to the pipeline's modality pool

* feat(automate): add ConvertAudioControls pipeline step (exemplar)

* feat(automate): add video tool settings controls to pipelines

* feat(automate): add audio tool settings controls to pipelines

* feat(automate): add document tool settings controls to pipelines

* feat(automate): add chart-maker settings control to pipelines

* feat(automate): warn on modality-incompatible pipeline steps

* feat(automate): add single-file download button for pipeline results

* refactor(automate): modality-aware icons, nav handler rename, mobile size bar

* test(pipeline): cover audio, document, file, and cross-modality chains

* i18n(automate): translate the modality-warning tooltip

* test(pipeline): gate media-pool routing assertion on ffmpeg availability

tests/unit/shared/modality-helpers.test.ts

@@ -0,0 +1,51 @@
+import { describe, expect, it } from "vitest";
+import { TOOLS } from "../../../packages/shared/src/constants.js";
+import {
+  modalityForExtension,
+  toolInputModality,
+  toolOutputModality,
+} from "../../../packages/shared/src/modality.js";
+
+const tool = (id: string) => {
+  const t = TOOLS.find((x) => x.id === id);
+  if (!t) throw new Error(`tool ${id} not found`);
+  return t;
+};
+
+describe("modalityForExtension", () => {
+  it("maps extensions to their owning modality", () => {
+    expect(modalityForExtension(".png")).toBe("image");
+    expect(modalityForExtension(".mp4")).toBe("video");
+    expect(modalityForExtension(".mp3")).toBe("audio");
+    expect(modalityForExtension(".pdf")).toBe("document");
+    expect(modalityForExtension(".csv")).toBe("file");
+  });
+  it("is case-insensitive and tolerates a missing dot", () => {
+    expect(modalityForExtension("PNG")).toBe("image");
+    expect(modalityForExtension(".JPG")).toBe("image");
+  });
+  it("returns null for unknown extensions", () => {
+    expect(modalityForExtension(".xyz")).toBeNull();
+  });
+});
+
+describe("toolOutputModality", () => {
+  it("defaults to the tool's modality", () => {
+    expect(toolOutputModality(tool("resize"))).toBe("image");
+  });
+  it("uses the override for crossing tools", () => {
+    expect(toolOutputModality(tool("extract-audio"))).toBe("audio");
+    expect(toolOutputModality(tool("chart-maker"))).toBe("image");
+  });
+});
+
+describe("toolInputModality", () => {
+  it("returns the tool modality for normal tools", () => {
+    expect(toolInputModality(tool("trim-video"))).toBe("video");
+    expect(toolInputModality(tool("compress-pdf"))).toBe("document");
+  });
+  it("derives the real input modality from acceptedInputs", () => {
+    expect(toolInputModality(tool("gif-to-video"))).toBe("image");
+    expect(toolInputModality(tool("chart-maker"))).toBe("file");
+  });
+});