Refactor authentication system: centralize credential handling in Builder

Major architectural improvement to eliminate duplicate credential embedding
and simplify authentication logic across the codebase.

Changes:
- Builder now generates all URL variants with proper authentication upfront
  * RTSP: generates URLs with embedded credentials and without (for open cameras)
  * HTTP/JPEG/MJPEG: generates variants with query params and for Basic Auth
- Tester simplified to only test ready-to-use URLs without modification
  * Removed auth chain logic and multiple authentication method attempts
  * Removed AuthMethod enum and related complexity
  * Credentials automatically extracted from URLs when needed
- Scanner cleaned up by removing embedCredentialsInURL function
  * All TestStream calls now use single URL parameter
  * Removed AuthMethod from DiscoveredStream model

Benefits:
- Eliminates bug where credentials were added up to 3 times
- Centralizes all URL generation logic in one place (Builder)
- Cleaner, more maintainable code with clear separation of concerns
- Reduces complexity by ~200 lines of code
- All authentication scenarios still fully supported

.github/workflows/release.yml

@@ -0,0 +1,32 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions:
+  contents: write
+
+jobs:
+  goreleaser:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '1.23'
+
+      - name: Run GoReleaser
+        uses: goreleaser/goreleaser-action@v6
+        with:
+          distribution: goreleaser
+          version: latest
+          args: release --clean
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}