Initial commit: React frontend (SLP Software) + AIDLC workflow docs

Co-authored-by: Junie <junie@jetbrains.com>

src/theme/tokens.ts

@@ -0,0 +1,30 @@
+/**
+ * Theme values (BR-3: only 'red' and 'purple' are valid).
+ * Actual token colors live in src/index.css (.theme-red / .theme-purple);
+ * this module only owns the *selectable* theme identifiers and the
+ * localStorage key used for persistence (BR-2).
+ */
+
+export type ThemeName = 'red' | 'purple';
+
+export const THEMES: ThemeName[] = ['red', 'purple'];
+
+export const DEFAULT_THEME: ThemeName = 'red';
+
+export const THEME_STORAGE_KEY = 'slp-software-theme';
+
+/** BR-3: fall back to the default theme for anything that isn't a valid ThemeName. */
+export function isValidTheme(value: unknown): value is ThemeName {
+  return value === 'red' || value === 'purple';
+}
+
+export function resolveInitialTheme(storedValue: string | null): ThemeName {
+  if (isValidTheme(storedValue)) {
+    return storedValue;
+  }
+  return DEFAULT_THEME;
+}
+
+export function themeClassName(theme: ThemeName): string {
+  return `theme-${theme}`;
+}