refactor(electrobun): modularize stores + shared UI components

Stores:
- notifications-store.svelte.ts: owns notifications array (was inline in App)
- workspace-store.svelte.ts: extended with addProjectFromWizard, loadGroupsFromDb,
  loadProjectsFromDb, derived getters (totalCost, totalTokens, mountedGroupIds)

Shared UI components (ui/):
- SegmentedControl.svelte: replaces repeated .seg button groups
- SliderInput.svelte: labeled range slider with value display
- StatusDot.svelte: colored dot with pulse support
- IconButton.svelte: icon-only button with tooltip, 3 sizes
- Section.svelte: settings section wrapper with heading

App.svelte: script 390→221 lines (removed all inline CRUD, delegates to stores)
ProjectCard: uses StatusDot shared component
AgentSettings + OrchestrationSettings: use SegmentedControl, SliderInput, Section

ui-electrobun/src/mainview/ProjectCard.svelte

@@ -7,6 +7,7 @@
   import TaskBoardTab from './TaskBoardTab.svelte';
   import DocsTab from './DocsTab.svelte';
   import SshTab from './SshTab.svelte';
+  import StatusDot from './ui/StatusDot.svelte';
   import {
     startAgent, stopAgent, sendPrompt, getSession, hasSession,
     loadLastSession,
@@ -162,12 +163,7 @@
   <!-- Header -->
   <header class="project-header">
     <div class="status-dot-wrap" aria-label="Status: {agentStatus}">
-      <div
-        class="status-dot {agentStatus}"
-        class:blink-off={agentStatus === 'running' && !blinkVisible}
-        role="img"
-        aria-label={agentStatus}
-      ></div>
+      <StatusDot status={agentStatus} blinkOff={agentStatus === 'running' && !blinkVisible} />
     </div>
 
     <span class="project-name" title={name}>{name}</span>
@@ -476,19 +472,6 @@
     position: relative;
   }
 
-  .status-dot {
-    width: 100%;
-    height: 100%;
-    border-radius: 50%;
-    background: var(--ctp-overlay0);
-  }
-
-  .status-dot.running { background: var(--ctp-green); }
-  .status-dot.idle    { background: var(--ctp-overlay1); }
-  .status-dot.done    { background: var(--ctp-green); }
-  .status-dot.error   { background: var(--ctp-red); }
-  .status-dot.stalled { background: var(--ctp-peach); }
-  .status-dot.blink-off { opacity: 0.3; }
 
   .project-name {
     font-weight: 600;