feat: copper accent theme, always-expanded group filter, app icon; rename MyPass to KeeVault

- Custom copper AccentColor and warm VaultBackground color assets (light/dark),
  applied to both the main app and the AutoFill extension (which needed its own
  copy of the asset catalog plus ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME
  and an explicit .tint() modifier, since extensions don't pick up the app-wide
  accent color the same way a full SwiftUI App/Scene does).
- GroupFilterView no longer uses DisclosureGroup for subgroups -- the whole tree
  renders always-expanded (indented per depth) so active filters are visible at
  a glance instead of requiring tap-to-expand.
- Added a placeholder app icon (padlock glyph, light/dark/tinted variants plus
  macOS sizes) -- previously the icon slot existed but had no actual images,
  which blocks App Store/TestFlight archive validation.
- Added ITSAppUsesNonExemptEncryption = NO (standard encryption only, via
  KeePassKit) to skip the export-compliance prompt on each upload.
- Renamed the app from MyPass to KeeVault throughout: Xcode project/targets/
  schemes, the MyPassCore package (now KeeVaultCore) and every import site,
  folder and file names, bundle identifiers (org.antiloop222.keevault) and
  their App Group/Keychain-group entitlements, and remaining UI/string
  references -- MyPass was already taken as an App Store app name.

AutoFill/Views/CredentialListView.swift

@@ -1,6 +1,6 @@
 // AutoFill/Views/CredentialListView.swift
 import SwiftUI
-import MyPassCore
+import KeeVaultCore
 
 struct CredentialListView: View {
     @ObservedObject var vm: ExtensionViewModel
@@ -40,6 +40,8 @@ struct CredentialListView: View {
                 }
             }
         }
+        .scrollContentBackground(.hidden)
+        .background(Color("VaultBackground"))
         .searchable(text: $searchQuery, prompt: "Search…")
     }
 }