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.

KeeVaultCore/Package.swift

@@ -0,0 +1,26 @@
+// swift-tools-version: 5.9
+import PackageDescription
+
+let package = Package(
+    name: "KeeVaultCore",
+    platforms: [.iOS(.v17), .macOS(.v14)],
+    products: [
+        .library(name: "KeeVaultCore", targets: ["KeeVaultCore"]),
+    ],
+    dependencies: [
+        .package(path: "../Vendor/KeePassKit"),
+    ],
+    targets: [
+        .target(
+            name: "KeeVaultCore",
+            dependencies: [
+                .product(name: "KeePassKit", package: "KeePassKit"),
+            ]
+        ),
+        .testTarget(
+            name: "KeeVaultCoreTests",
+            dependencies: ["KeeVaultCore"],
+            resources: [.copy("Fixtures")]
+        ),
+    ]
+)