FN-6256: enforce recursive raw rgba CSS hygiene

Extend the dashboard component CSS hygiene guard so raw rgb/rgba checks cover nested component styles.

- Recursively discover dashboard component CSS files instead of only scanning the top-level components directory.
- Report stable component-relative paths for violations across nested folders.
- Add focused coverage for raw rgba detection while preserving var() fallback allowance.

Files changed:
 .../__tests__/component-css-no-raw-rgba.test.ts    | 85 +++++++++++++++++-----
 1 file changed, 65 insertions(+), 20 deletions(-)

Fusion-Task-Id: FN-6256

Fusion-Task-Lineage: c8e84ab4-1da9-4cf0-9e04-d8ca4038eafa

packages/dashboard/app/__tests__/component-css-no-raw-rgba.test.ts

@@ -1,5 +1,5 @@
 import { readdirSync, readFileSync } from "node:fs";
-import { join, resolve } from "node:path";
+import { join, relative, resolve, sep } from "node:path";
 import { describe, expect, it } from "vitest";
 
 const componentsDir = resolve(__dirname, "..", "components");
@@ -8,27 +8,72 @@ function stripVarFallbackRgba(content: string): string {
   return content.replace(/var\([^()]*,\s*rgba?\([^)]*\)\s*\)/g, "");
 }
 
-describe("component CSS color token hygiene", () => {
-  it("contains no raw rgb/rgba calls outside var() fallbacks", () => {
-    const cssFiles = readdirSync(componentsDir)
-      .filter((name) => name.endsWith(".css"))
-      .sort();
+function findComponentCssFiles(dir = componentsDir): string[] {
+  const entries = readdirSync(dir, { withFileTypes: true });
+  const files = entries.flatMap((entry) => {
+    const entryPath = join(dir, entry.name);
 
-    const violations: string[] = [];
-
-    for (const fileName of cssFiles) {
-      const filePath = join(componentsDir, fileName);
-      const source = readFileSync(filePath, "utf8");
-      const withoutFallbacks = stripVarFallbackRgba(source);
-      const lines = withoutFallbacks.split(/\r?\n/);
-
-      for (let index = 0; index < lines.length; index += 1) {
-        if (/rgba?\(/.test(lines[index])) {
-          violations.push(`${fileName}:${index + 1}:${lines[index].trim()}`);
-        }
-      }
+    if (entry.isDirectory()) {
+      return findComponentCssFiles(entryPath);
     }
 
-    expect(violations).toEqual([]);
+    return entry.isFile() && entry.name.endsWith(".css") ? [entryPath] : [];
+  });
+
+  return files.sort((left, right) =>
+    relative(componentsDir, left).localeCompare(relative(componentsDir, right))
+  );
+}
+
+function formatComponentCssPath(filePath: string): string {
+  return relative(componentsDir, filePath).split(sep).join("/");
+}
+
+function findRawRgbViolations(source: string, fileName: string): string[] {
+  const withoutFallbacks = stripVarFallbackRgba(source);
+  const lines = withoutFallbacks.split(/\r?\n/);
+
+  return lines.flatMap((line, index) =>
+    /rgba?\(/.test(line) ? [`${fileName}:${index + 1}:${line.trim()}`] : []
+  );
+}
+
+function buildRawRgbFailureMessage(violations: string[]): string {
+  return [
+    "Raw rgb/rgba() found in component CSS.",
+    "Use design tokens or color-mix(in srgb, var(--color-X) N%, transparent) instead:",
+    ...violations,
+  ].join("\n");
+}
+
+describe("component CSS color token hygiene", () => {
+  it("detects raw rgb/rgba calls but permits var() fallback rgb/rgba", () => {
+    const source = [
+      ".clean { color: var(--color-text); }",
+      ".fallback { color: var(--custom-color, rgba(1, 2, 3, 0.5)); }",
+      ".violation { box-shadow: 0 0 0 1px rgba(1, 2, 3, 0.5); }",
+    ].join("\n");
+
+    const violations = findRawRgbViolations(source, "fixture.css");
+
+    expect(violations).toEqual([
+      "fixture.css:3:.violation { box-shadow: 0 0 0 1px rgba(1, 2, 3, 0.5); }",
+    ]);
+    expect(buildRawRgbFailureMessage(violations)).toContain(
+      "fixture.css:3:.violation { box-shadow: 0 0 0 1px rgba(1, 2, 3, 0.5); }"
+    );
+    expect(buildRawRgbFailureMessage(violations)).toContain(
+      "color-mix(in srgb, var(--color-X) N%, transparent)"
+    );
+  });
+
+  it("contains no raw rgb/rgba calls outside var() fallbacks", () => {
+    const cssFiles = findComponentCssFiles();
+
+    const violations = cssFiles.flatMap((filePath) =>
+      findRawRgbViolations(readFileSync(filePath, "utf8"), formatComponentCssPath(filePath))
+    );
+
+    expect(violations, buildRawRgbFailureMessage(violations)).toEqual([]);
   });
 });