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/lib/components/MicrobreakOverlay.svelte

@@ -0,0 +1,80 @@
+<script lang="ts">
+  import { onMount } from "svelte";
+  import { listen } from "@tauri-apps/api/event";
+  import { invoke } from "@tauri-apps/api/core";
+  import type { TimerSnapshot } from "../stores/timer";
+  import { loadConfig, config } from "../stores/config";
+  import { pickRandomActivity, getCategoryLabel, type BreakActivity } from "../utils/activities";
+
+  let timeRemaining = $state(20);
+  let totalDuration = $state(20);
+  let activity = $state<BreakActivity | null>(null);
+
+  const progress = $derived(totalDuration > 0 ? 1 - timeRemaining / totalDuration : 0);
+
+  onMount(async () => {
+    await loadConfig();
+
+    if ($config.microbreak_show_activity) {
+      // Pick an eye-focused activity for microbreaks
+      activity = pickRandomActivity(undefined, $config);
+    }
+
+    try {
+      const snap = await invoke<TimerSnapshot>("get_timer_state");
+      timeRemaining = snap.microbreakTimeRemaining;
+      totalDuration = snap.microbreakTotalDuration;
+    } catch {}
+
+    await listen<TimerSnapshot>("timer-tick", (event) => {
+      const snap = event.payload;
+      timeRemaining = snap.microbreakTimeRemaining;
+      totalDuration = snap.microbreakTotalDuration;
+    });
+
+    await listen("microbreak-ended", () => {
+      // Window will be closed by backend
+    });
+  });
+</script>
+
+<div class="microbreak-card">
+  <div class="flex items-center gap-3 mb-2">
+    <svg aria-hidden="true" width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="#7c6aef" stroke-width="1.5">
+      <path d="M2.036 12.322a1.012 1.012 0 0 1 0-.639C3.423 7.51 7.36 4.5 12 4.5c4.638 0 8.573 3.007 9.963 7.178.07.207.07.431 0 .639C20.577 16.49 16.64 19.5 12 19.5c-4.638 0-8.573-3.007-9.963-7.178Z"/>
+      <circle cx="12" cy="12" r="3"/>
+    </svg>
+    <span class="text-[15px] font-medium text-white">Look away — 20 feet for {timeRemaining}s</span>
+  </div>
+
+  {#if activity && $config.microbreak_show_activity}
+    <p class="text-[12px] text-[#8a8a8a] mb-3 ml-[34px]">
+      {activity.text}
+    </p>
+  {/if}
+
+  <!-- Progress bar -->
+  <div class="h-[3px] w-full rounded-full overflow-hidden" style="background: rgba(255,255,255,0.05);">
+    <div
+      class="h-full transition-[width] duration-1000 ease-linear rounded-full"
+      style="width: {progress * 100}%; background: linear-gradient(to right, #7c6aef, #4361ee);"
+    ></div>
+  </div>
+</div>
+
+<style>
+  .microbreak-card {
+    position: fixed;
+    top: 16px;
+    left: 50%;
+    transform: translateX(-50%);
+    width: 380px;
+    background: rgba(12, 12, 12, 0.95);
+    backdrop-filter: blur(24px);
+    -webkit-backdrop-filter: blur(24px);
+    border: 1px solid rgba(255, 255, 255, 0.08);
+    border-radius: 16px;
+    padding: 16px 20px;
+    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.5);
+  }
+</style>