feat: implement GuideController for evolution guide panel

- Added GuideController to manage the evolution guide panel, including event listeners for opening/closing the panel and spawning entities.
- Introduced a new guide.js file with the GuideController implementation.
- Created guide.css for styling the guide panel and its elements.
- Updated main.js to initialize the GuideController and link it with the EvolutionController.
- Enhanced settings.js to include functionality for resetting settings to defaults and saving state to localStorage.
- Modified modal.css to improve the layout and styling of the modal footer and reset button.
- Adjusted main.css to unify button styles for settings and guide buttons.
- Updated icons.css to add animations for entity interactions.
- Refactored gradient.js to utilize constants for default values.

src/js/main.js

@@ -14,12 +14,14 @@ import { GradientController }  from './gradient.js';
 import { ModalController }     from './modal.js';
 import { SettingsController }  from './settings.js';
 import { EvolutionController } from './evolution.js';
+import { GuideController }     from './guide.js';
 import { DEFAULTS }            from './constants.js';
 
 // ── Initialise controllers ─────────────────────────────────
 const gradient  = new GradientController();
 const modal     = new ModalController();
 const evolution = new EvolutionController();
+const guide     = new GuideController();
 
 // SettingsController bridges UI → gradient + evolution
 // eslint-disable-next-line no-unused-vars
@@ -30,8 +32,14 @@ document.getElementById('settingsBtn').addEventListener('click', (e) => {
   modal.open(/** @type {HTMLElement} */ (e.currentTarget));
 });
 
+// ── Wire up evolution guide ────────────────────────────────
+guide.init(evolution);
+
 // ── Boot gradient ──────────────────────────────────────────
 gradient.init(DEFAULTS.GRADIENT_COLOR);
 
+// Apply saved settings after gradient has set its defaults
+settings.loadSaved();
+
 // ── Boot evolution (async — loads icons.json + warms SVG cache) ──
 evolution.init(document.getElementById('evolutionContainer'));