feat: plugin install/uninstall lifecycle + UI buttons

- AppConfig: add InstalledPlugins []string
- Manager.Discover(): no config dependency, all plugins start inactive
- Manager.SyncConfig(): apply installed/enabled state from AppConfig
- Manager.Enable(): works for plugins without on_install hook
- Manager.Install/Uninstall(): run on_install/on_uninstall hooks
- ActivatePlugin: skip if HasInstall && !Installed
- ReloadPlugins: Discover → SyncConfig → InitRuntimes
- Bindings: InstallPlugin, UninstallPlugin
- SettingsPlugins: install/uninstall buttons, toggle only after install
- Calendar: migration moved from on_init to on_install, on_uninstall drops tables
- Tests: all 12 pass (manager + runtime + calendar)

frontend/src/lib/SettingsPlugins.svelte

@@ -35,6 +35,31 @@
     }
   }
 
+  async function install(p) {
+    error = ''
+    try {
+      await wailsCall('InstallPlugin', p.name)
+      p.installed = true
+      // Refresh list to reflect new state
+      plugins = await wailsCall('ListPlugins') || []
+    } catch (e) {
+      error = String(e)
+    }
+  }
+
+  async function uninstall(p) {
+    if (!confirm(`Удалить плагин «${p.name}»? Все данные плагина будут очищены. Файлы плагина сохранятся.`)) return
+    error = ''
+    try {
+      await wailsCall('UninstallPlugin', p.name)
+      p.installed = false
+      p.active = false
+      plugins = await wailsCall('ListPlugins') || []
+    } catch (e) {
+      error = String(e)
+    }
+  }
+
   $: sidebarCount = plugins.reduce((n, p) => n + (p.uiContribs?.sidebarItems?.length || 0), 0)
   $: tabCount = plugins.reduce((n, p) => n + (p.uiContribs?.nodeTabs?.length || 0), 0)
 </script>
@@ -82,15 +107,36 @@
             </div>
           </div>
           <div class="plugin-toggle">
-            <button
-              class="toggle-btn"
-              class:active={p.active}
-              on:click={() => toggle(p)}
-              role="switch"
-              aria-checked={p.active}
-            >
-              <span class="toggle-knob"></span>
-            </button>
+            {#if p.hasInstall && !p.installed}
+              <button class="install-btn" on:click={() => install(p)}>
+                📦 Установить
+              </button>
+            {:else if p.hasInstall && p.installed}
+              <div class="toggle-group">
+                <button
+                  class="toggle-btn"
+                  class:active={p.active}
+                  on:click={() => toggle(p)}
+                  role="switch"
+                  aria-checked={p.active}
+                >
+                  <span class="toggle-knob"></span>
+                </button>
+                <button class="uninstall-btn btn-sm" on:click={() => uninstall(p)} title="Удалить плагин (очистить данные)">
+                  🗑
+                </button>
+              </div>
+            {:else}
+              <button
+                class="toggle-btn"
+                class:active={p.active}
+                on:click={() => toggle(p)}
+                role="switch"
+                aria-checked={p.active}
+              >
+                <span class="toggle-knob"></span>
+              </button>
+            {/if}
           </div>
         </div>
       {/each}
@@ -201,4 +247,42 @@
   .toggle-btn.active .toggle-knob {
     left: 22px;
   }
+
+  .toggle-group {
+    display: flex;
+    align-items: center;
+    gap: 6px;
+  }
+
+  .install-btn {
+    padding: 6px 14px;
+    background: #6366f1;
+    color: #fff;
+    border: none;
+    border-radius: 6px;
+    cursor: pointer;
+    font-size: 13px;
+    white-space: nowrap;
+  }
+  .install-btn:hover { filter: brightness(1.15); }
+
+  .uninstall-btn {
+    width: 28px;
+    height: 28px;
+    background: var(--surface, #1a1a2e);
+    color: #ef4444;
+    border: 1px solid rgba(239,68,68,0.3);
+    border-radius: 6px;
+    cursor: pointer;
+    font-size: 14px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    opacity: 0.6;
+    transition: all 0.15s;
+  }
+  .uninstall-btn:hover {
+    opacity: 1;
+    background: rgba(239,68,68,0.1);
+  }
 </style>