Add pomodoro, microbreaks, breathing guide, screen dimming, presentation mode, goals, multi-monitor, and activity manager

Major feature release (v0.1.3) adding 15 new features to the break timer:

Backend (Rust):
- Pomodoro cycle tracking with configurable short/long break pattern
- Microbreak scheduling (20-20-20 rule) with independent timer
- Screen dimming events with gradual opacity progression
- Presentation mode detection (fullscreen app deferral)
- Smart break detection (natural idle breaks counting toward goals)
- Daily goal tracking and streak milestone events
- Multi-monitor break overlay support
- Working hours enforcement with per-day schedules
- Weekly summary and natural break stats queries
- Config expanded to 71 validated fields

Frontend (Svelte):
- 6 new components: BreathingGuide, ActivityManager, BreakOverlay,
  MicrobreakOverlay, DimOverlay, Celebration
- Breathing guide with 5 patterns and animated pulsing halo
- Activity manager with favorites, custom activities, momentum scroll
- Confetti celebrations on milestones and goal completion
- Dashboard indicators (pomodoro/microbreak/goal) moved inside ring
- Settings reorganized into 18 logical cards
- Breathing pattern selector redesigned with timing descriptions
- Break activities expanded from 40 to 71 curated exercises
- Sound presets expanded from 4 to 8
- Stats view with weekly summary and natural break tracking

Also: version bump to 0.1.3, CHANGELOG, README and CLAUDE.md updates

src/main.ts

@@ -2,19 +2,35 @@ import "./app.css";
 import App from "./App.svelte";
 import MiniTimer from "./lib/components/MiniTimer.svelte";
 import BreakWindow from "./lib/components/BreakWindow.svelte";
+import MicrobreakOverlay from "./lib/components/MicrobreakOverlay.svelte";
+import DimOverlay from "./lib/components/DimOverlay.svelte";
+import BreakOverlay from "./lib/components/BreakOverlay.svelte";
 import { mount } from "svelte";
 
 const params = new URLSearchParams(window.location.search);
+const isMicrobreak = params.has("microbreak");
+const isDim = params.has("dim");
+const isBreakOverlay = params.has("breakoverlay");
 const isMini = params.has("mini");
 const isBreak = params.has("break");
 
-if (isMini || isBreak) {
+if (isMini || isBreak || isMicrobreak || isDim || isBreakOverlay) {
   // Transparent body so rounded shapes show through the transparent window
   document.body.style.background = "transparent";
   document.documentElement.style.background = "transparent";
 }
 
-const component = isMini ? MiniTimer : isBreak ? BreakWindow : App;
+const component = isMicrobreak
+  ? MicrobreakOverlay
+  : isDim
+    ? DimOverlay
+    : isBreakOverlay
+      ? BreakOverlay
+      : isMini
+        ? MiniTimer
+        : isBreak
+          ? BreakWindow
+          : App;
 
 const app = mount(component, {
   target: document.getElementById("app")!,