fix(FN-2365): tokenize Git Manager light-theme surface styles

- Add semantic neutral surface tier tokens in root and light-theme blocks for subtle, muted, emphasis, and stronger hover states
- Replace Git Manager light-theme hardcoded neutral rgba backgrounds with surface tokens and token-based color-mix accent states
- Add dedicated Git Manager theme styling tests to guard token usage and prevent regressions to raw rgba values
- Expand status color/theme token tests and stabilize SettingsModal navigation selectors used by related test coverage

packages/dashboard/app/__tests__/git-manager-theme-styling.test.ts

@@ -0,0 +1,54 @@
+import { describe, it, expect, beforeAll } from "vitest";
+import fs from "fs";
+import path from "path";
+
+describe("Git Manager light-theme tokenization", () => {
+  const stylesPath = path.resolve(__dirname, "../styles.css");
+  let css: string;
+
+  beforeAll(() => {
+    css = fs.readFileSync(stylesPath, "utf-8");
+  });
+
+  function getGitManagerLightBlock(): string {
+    const startMarker = "/* ── Light Theme Overrides ── */";
+    const endMarker = "/* ── Task Changes Tab Styles";
+
+    const startIdx = css.indexOf(startMarker);
+    const endIdx = css.indexOf(endMarker);
+
+    if (startIdx === -1 || endIdx === -1 || endIdx <= startIdx) {
+      throw new Error("Could not locate Git Manager light-theme override block boundaries");
+    }
+
+    return css.slice(startIdx, endIdx);
+  }
+
+  it("uses semantic neutral surface tokens for scoped Git Manager light-theme backgrounds", () => {
+    const block = getGitManagerLightBlock();
+
+    expect(block).toContain('[data-theme="light"] .gm-sidebar {\n  background: var(--surface-subtle);');
+    expect(block).toContain('[data-theme="light"] .gm-nav-item:hover {\n  background: var(--surface-hover);');
+    expect(block).toContain('[data-theme="light"] .gm-commit-header:hover {\n  background: var(--surface-muted);');
+    expect(block).toContain('[data-theme="light"] .gm-hash {\n  background: var(--surface-emphasis);');
+    expect(block).toContain('[data-theme="light"] .gm-icon-btn:hover {\n  background: var(--surface-hover-strong);');
+  });
+
+  it("does not reintroduce direct neutral rgba(0,0,0,0.02-0.06) backgrounds in scoped Git Manager light-theme rules", () => {
+    const block = getGitManagerLightBlock();
+
+    expect(block).not.toMatch(/background:\s*rgba\(0,\s*0,\s*0,\s*0\.0[2-6]\)/);
+  });
+
+  it("uses token-based accent states for selected/default Git Manager light-theme rules", () => {
+    const block = getGitManagerLightBlock();
+
+    expect(block).toContain("color-mix(in srgb, var(--todo) 8%, transparent)");
+    expect(block).toContain("color-mix(in srgb, var(--todo) 12%, transparent)");
+    expect(block).toContain("color-mix(in srgb, var(--todo) 10%, transparent)");
+    expect(block).toContain("color: var(--todo);");
+
+    expect(block).not.toContain("rgba(9, 105, 218");
+    expect(block).not.toContain("#0969da");
+  });
+});