feat: avatar upload via presigned PUT URL flow

- Go scraper: add PresignAvatarUploadURL/PresignAvatarURL/DeleteAvatar to
  Store interface, implement on HybridStore+MinioClient, register
  GET /api/presign/avatar-upload/{userId} and /api/presign/avatar/{userId}
- SvelteKit: replace direct AWS S3 SDK in minio.ts with presign calls to
  the Go scraper; rewrite avatar +server.ts (POST=presign, PATCH=record key)
- iOS: rewrite uploadAvatar() as 3-step presigned PUT flow; refactor
  chip components into shared ChipButton in CommonViews.swift

ios/LibNovel/LibNovel.xcodeproj/xcshareddata/xcschemes/LibNovel.xcscheme

@@ -1,11 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1600"
-   version = "1.7">
+   LastUpgradeVersion = "2630"
+   version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
-      buildImplicitDependencies = "YES"
-      runPostActionsOnFailure = "NO">
+      buildImplicitDependencies = "YES">
       <BuildActionEntries>
          <BuildActionEntry
             buildForTesting = "YES"
@@ -27,8 +26,7 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
-      shouldUseLaunchSchemeArgsEnv = "YES"
-      onlyGenerateCoverageForSpecifiedTargets = "NO">
+      shouldUseLaunchSchemeArgsEnv = "YES">
       <MacroExpansion>
          <BuildableReference
             BuildableIdentifier = "primary"
@@ -51,8 +49,6 @@
             </BuildableReference>
          </TestableReference>
       </Testables>
-      <CommandLineArguments>
-      </CommandLineArguments>
    </TestAction>
    <LaunchAction
       buildConfiguration = "Debug"
@@ -74,8 +70,6 @@
             ReferencedContainer = "container:LibNovel.xcodeproj">
          </BuildableReference>
       </BuildableProductRunnable>
-      <CommandLineArguments>
-      </CommandLineArguments>
       <EnvironmentVariables>
          <EnvironmentVariable
             key = "LIBNOVEL_BASE_URL"
@@ -100,8 +94,6 @@
             ReferencedContainer = "container:LibNovel.xcodeproj">
          </BuildableReference>
       </BuildableProductRunnable>
-      <CommandLineArguments>
-      </CommandLineArguments>
    </ProfileAction>
    <AnalyzeAction
       buildConfiguration = "Debug">