fix: Force clean Rust toolchain to resolve SIGSEGV compilation errors

- Add rustup toolchain install stable --force to ensure clean toolchain
- Clear cargo cache to avoid corruption issues
- Resolves Rust compilation SIGSEGV errors in CI environment
- Ensures stable Rust toolchain is properly installed and cached

Fixes build failures caused by corrupted Rust toolchain in rust:trixie container.

.forgejo/workflows/ci.yml

@@ -81,13 +81,18 @@ jobs:
           rustc --version
           cargo --version
 
-          # Force stable Rust to avoid SIGSEGV bugs in 1.89.0
-          echo "🔧 Forcing stable Rust toolchain..."
+          # Force clean Rust toolchain to avoid SIGSEGV bugs
+          echo "🔧 Forcing clean stable Rust toolchain..."
           rustup default stable
           rustup update stable
-          echo "✅ Now using stable Rust:"
+          rustup toolchain install stable --force
+          echo "✅ Now using clean stable Rust:"
           rustc --version
           cargo --version
+          
+          # Clear cargo cache to avoid corruption
+          echo "🧹 Clearing cargo cache..."
+          cargo clean
 
       - name: Build project
         run: |