feat: add Forest, Mono, and Cyberpunk color themes

Forest — deep green surfaces (#0a130d base) with green-400 accent.
  Inspired by terminal emulators and dark mode IDE forest schemes.

Mono — near-black zinc-950 surface with pure white/zinc-100 accent.
  Minimal high-contrast monochromatic palette for distraction-free reading.

Cyber — near-black blue surface with neon cyan-400 accent and dracula-palette
  success/danger colors. Cyberpunk aesthetic with neon glow feel.

Changes:
- app.css: three new [data-theme] blocks with full token sets
- +layout.svelte: added forest/mono/cyber to THEMES array (before light themes)
- profile/+page.svelte: same additions with i18n label functions
- messages/*.json: translated names in all 5 locales (en/fr/ru/pt/id)

ui/src/routes/+layout.svelte

@@ -38,6 +38,9 @@
 		{ id: 'amber',       color: '#f59e0b' },
 		{ id: 'slate',       color: '#818cf8' },
 		{ id: 'rose',        color: '#fb7185' },
+		{ id: 'forest',      color: '#4ade80' },
+		{ id: 'mono',        color: '#f4f4f5' },
+		{ id: 'cyber',       color: '#22d3ee' },
 		{ id: 'light',       color: '#d97706', light: true },
 		{ id: 'light-slate', color: '#4f46e5', light: true },
 		{ id: 'light-rose',  color: '#e11d48', light: true },

ui/src/routes/profile/+page.svelte

@@ -145,6 +145,9 @@
 		{ id: 'amber',       label: () => m.profile_theme_amber(),       swatch: '#f59e0b' },
 		{ id: 'slate',       label: () => m.profile_theme_slate(),       swatch: '#818cf8' },
 		{ id: 'rose',        label: () => m.profile_theme_rose(),        swatch: '#fb7185' },
+		{ id: 'forest',      label: () => m.profile_theme_forest(),      swatch: '#4ade80' },
+		{ id: 'mono',        label: () => m.profile_theme_mono(),        swatch: '#f4f4f5' },
+		{ id: 'cyber',       label: () => m.profile_theme_cyber(),       swatch: '#22d3ee' },
 		{ id: 'light',       label: () => m.profile_theme_light(),       swatch: '#d97706', light: true },
 		{ id: 'light-slate', label: () => m.profile_theme_light_slate(), swatch: '#4f46e5', light: true },
 		{ id: 'light-rose',  label: () => m.profile_theme_light_rose(),  swatch: '#e11d48', light: true },