test: update pre-existing stale specs for 2.0 multimodal + validation behavior

Fixes a backlog of integration/unit specs that asserted pre-2.0 behavior and
were failing CI (not caused by recent feature work):
- modality-aware empty-input error is 'No file(s) provided', not /no image/i
  (rotate, border, crop, resize, smart-crop, edge-cases, adversarial-extended,
  api, tool-factory-route)
- input validation rejects pre-enqueue with a clean 400 in 'error' (was a worker
  422 in 'details'): create-zip, extract-zip, merge-csvs
- resolveToolPool defaults unknown tools to the system pool (pool-routing)
- /upload and fetch-urls accept non-image content, validated per-tool at process
  time (api, fetch-urls)
- color-adjust legacy aliases were consolidated into adjust-colors: drop the
  removed-alias tests; retarget the format-preservation tests
- xml-to-csv gracefully converts a single non-repeating record to a 1-row CSV
- dropzone is multimodal; image-only filtering is opt-in via fileFilter
- factory-multi-input: register the synthetic test tools in the catalog so they
  route correctly (file modality for concat; image for the validation-prefix test)

Verified locally: unit 4546 passed, integration 8332 passed, typecheck + lint green.

tests/integration/factory-multi-input.test.ts

@@ -7,6 +7,7 @@
  */
 import { readFileSync } from "node:fs";
 import { join } from "node:path";
+import { TOOLS } from "@snapotter/shared";
 import { eq } from "drizzle-orm";
 import { afterAll, beforeAll, describe, expect, it } from "vitest";
 import { db, schema } from "../../apps/api/src/db/index.js";
@@ -47,17 +48,66 @@ preReadyHooks.push((app) => {
       contentType: "application/octet-stream",
     }),
   });
+  // Image-modality multi-input tool: used to verify per-file validation errors
+  // are prefixed with the filename. (multi-concat is "file" modality, which
+  // passes content through without validating, so it cannot exercise this path.)
+  createToolRoute(app, {
+    toolId: "multi-validate",
+    maxInputs: 2,
+    settingsSchema: emptySchema,
+    process: async () => {
+      throw new Error("legacy path must not run");
+    },
+    processV2: async (ctx) => ({
+      buffer: ctx.inputs[0].buffer,
+      filename: "out.png",
+      contentType: "image/png",
+    }),
+  });
 });
 
 let testApp: TestApp;
 let adminToken: string;
 
 beforeAll(async () => {
+  // multi-concat isn't a real catalog tool. resolveToolPool() routes unknown
+  // tool IDs to the "system" pool (whose worker only runs system jobs), and the
+  // factory would default it to image modality (which re-encodes inputs). Register
+  // it as a "file" tool so it routes to the docs pool with raw passthrough, like a
+  // real multi-input file tool. Removed again in afterAll.
+  TOOLS.push(
+    {
+      id: "multi-concat",
+      name: "Multi Concat (test)",
+      description: "Test-only tool that concatenates inputs",
+      category: "archives",
+      icon: "FolderArchive",
+      route: "/multi-concat",
+      modality: "file",
+      acceptedInputs: [],
+      executionHint: "fast",
+    } as (typeof TOOLS)[number],
+    {
+      id: "multi-validate",
+      name: "Multi Validate (test)",
+      description: "Test-only image multi-input tool",
+      category: "archives",
+      icon: "Image",
+      route: "/multi-validate",
+      modality: "image",
+      acceptedInputs: [],
+      executionHint: "fast",
+    } as (typeof TOOLS)[number],
+  );
   testApp = await buildTestApp();
   adminToken = await loginAsAdmin(testApp.app);
 }, 30_000);
 
 afterAll(async () => {
+  for (const id of ["multi-concat", "multi-validate"]) {
+    const idx = TOOLS.findIndex((t) => t.id === id);
+    if (idx !== -1) TOOLS.splice(idx, 1);
+  }
   await testApp.cleanup();
 }, 10_000);
 
@@ -161,7 +211,7 @@ describe("Factory multi-input (maxInputs)", () => {
 
     const res = await testApp.app.inject({
       method: "POST",
-      url: "/api/v1/tools/multi-concat",
+      url: "/api/v1/tools/multi-validate",
       headers: {
         authorization: `Bearer ${adminToken}`,
         "content-type": contentType,