feat(ext/shared): color-scheme storage + applyColorScheme

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

extension/src/shared/color-scheme.ts

@@ -0,0 +1,48 @@
+export const DEFAULT_DIGIT_COLOR = '#2563eb';
+export const DEFAULT_SYMBOL_COLOR = '#dc2626';
+const STORAGE_KEY = 'password_display_scheme';
+const HEX_RE = /^#[0-9a-fA-F]{6}$/;
+
+export interface ColorScheme {
+  digit_color: string;
+  symbol_color: string;
+}
+
+export const DEFAULT_SCHEME: ColorScheme = {
+  digit_color: DEFAULT_DIGIT_COLOR,
+  symbol_color: DEFAULT_SYMBOL_COLOR,
+};
+
+function isValid(s: ColorScheme): boolean {
+  return HEX_RE.test(s.digit_color) && HEX_RE.test(s.symbol_color);
+}
+
+export async function loadColorScheme(): Promise<ColorScheme> {
+  const result = await chrome.storage.sync.get(STORAGE_KEY);
+  const stored = result[STORAGE_KEY] as Partial<ColorScheme> | undefined;
+  if (!stored) return { ...DEFAULT_SCHEME };
+  return {
+    digit_color: typeof stored.digit_color === 'string' && HEX_RE.test(stored.digit_color)
+      ? stored.digit_color : DEFAULT_DIGIT_COLOR,
+    symbol_color: typeof stored.symbol_color === 'string' && HEX_RE.test(stored.symbol_color)
+      ? stored.symbol_color : DEFAULT_SYMBOL_COLOR,
+  };
+}
+
+export async function saveColorScheme(scheme: ColorScheme): Promise<void> {
+  if (!isValid(scheme)) {
+    throw new Error('Invalid color values; expected #rrggbb hex strings.');
+  }
+  await chrome.storage.sync.set({ [STORAGE_KEY]: scheme });
+}
+
+export async function resetColorScheme(): Promise<void> {
+  await chrome.storage.sync.remove(STORAGE_KEY);
+}
+
+export async function applyColorScheme(): Promise<void> {
+  const scheme = await loadColorScheme();
+  const root = document.documentElement.style;
+  root.setProperty('--relicario-pwd-digit-color', scheme.digit_color);
+  root.setProperty('--relicario-pwd-symbol-color', scheme.symbol_color);
+}