feat: add backup file management settings

- Added settings UI to enable/disable .bak file creation when saving files
- Created settings storage in .obsidian/obsiviewer.json to persist backup preferences
- Added API endpoints to read/write backup settings (/api/settings)
- Implemented automatic cleanup of existing .bak files when disabling backups
- Modified file save operations to respect backup setting across notes, bookmarks and graph files
- Removed existing .bak files from version control

src/app/features/parameters/parameters.page.html

@@ -112,6 +112,34 @@
       </div>
     </section>
 
+    <!-- Backups Section -->
+    <section class="parameters-section">
+      <h2 class="section-title">
+        <svg class="section-icon" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+          <path d="M21 15v4a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2v-4"/>
+          <polyline points="7 10 12 15 17 10"/>
+          <line x1="12" y1="15" x2="12" y2="3"/>
+        </svg>
+        Backups (.bak files)
+      </h2>
+
+      <div class="setting-group">
+        <label class="setting-label">Enable backup files when saving</label>
+        <div class="toggle-switch">
+          <input 
+            type="checkbox" 
+            id="enableBackups"
+            [checked]="backupsEnabled()"
+            (change)="toggleBackups()"
+            class="toggle-input" />
+          <label for="enableBackups" class="toggle-label">
+            <span class="toggle-slider"></span>
+          </label>
+        </div>
+        <p class="setting-hint">When disabled, existing .bak files in the vault will be removed automatically.</p>
+      </div>
+    </section>
+
     <!-- Folder Filtering Section -->
     <section class="parameters-section">
       <h2 class="section-title">

src/app/features/parameters/parameters.page.ts

@@ -2,6 +2,7 @@ import { Component, inject, signal, effect } from '@angular/core';
 import { CommonModule } from '@angular/common';
 import { FormsModule } from '@angular/forms';
 import { ThemeService, ThemeMode, ThemeId, Language } from '../../core/services/theme.service';
+import { SettingsService } from '../../services/settings.service';
 import { ToastService } from '../../shared/toast/toast.service';
 import { FolderFilterService, FolderFilterConfig } from '../../services/folder-filter.service';
 
@@ -16,11 +17,13 @@ export class ParametersPage {
   private themeService = inject(ThemeService);
   private toastService = inject(ToastService);
   private folderFilterService = inject(FolderFilterService);
+  private settingsService = inject(SettingsService);
 
   // Reactive prefs
   prefs = signal(this.themeService.prefsValue);
   folderFilterConfig = signal<FolderFilterConfig>(this.folderFilterService.getConfig());
   newExcludedFolder = '';
+  backupsEnabled = signal<boolean>(true);
 
   modes: ThemeMode[] = ['system', 'light', 'dark'];
   themes: ThemeId[] = ['light', 'dark', 'obsidian', 'nord', 'notion', 'github', 'discord', 'monokai'];
@@ -47,6 +50,13 @@ export class ParametersPage {
       
       return () => subscription.unsubscribe();
     });
+
+    effect(() => {
+      const sub = this.settingsService.getSettings().subscribe(({ enableBackups }) => {
+        this.backupsEnabled.set(!!enableBackups);
+      });
+      return () => sub.unsubscribe();
+    });
   }
 
   setMode(mode: ThemeMode): void {
@@ -128,4 +138,18 @@ export class ParametersPage {
     this.folderFilterConfig.set(this.folderFilterService.getConfig());
     this.showToast('Folder filters reset to defaults');
   }
+
+  toggleBackups(): void {
+    const next = !this.backupsEnabled();
+    this.settingsService.updateBackups(next).subscribe((res) => {
+      this.backupsEnabled.set(res.enableBackups);
+      if (!res.enableBackups && (res.deletedBakFiles ?? 0) > 0) {
+        this.showToast(`Backups disabled. Deleted ${res.deletedBakFiles} .bak files`);
+      } else if (!res.enableBackups) {
+        this.showToast('Backups disabled');
+      } else {
+        this.showToast('Backups enabled');
+      }
+    });
+  }
 }

src/app/services/settings.service.ts

@@ -0,0 +1,26 @@
+import { Injectable, inject } from '@angular/core';
+import { HttpClient } from '@angular/common/http';
+import { Observable, map } from 'rxjs';
+
+export interface AppSettings {
+  enableBackups: boolean;
+}
+
+@Injectable({ providedIn: 'root' })
+export class SettingsService {
+  private http = inject(HttpClient);
+
+  getSettings(): Observable<AppSettings> {
+    return this.http.get<AppSettings>('/api/settings').pipe(
+      map((res) => ({ enableBackups: res?.enableBackups !== false }))
+    );
+  }
+
+  updateBackups(enableBackups: boolean): Observable<{ success: boolean; enableBackups: boolean; deletedBakFiles?: number }>
+  {
+    return this.http.put<{ success: boolean; enableBackups: boolean; deletedBakFiles?: number }>(
+      '/api/settings',
+      { enableBackups }
+    );
+  }
+}