feat: register wasmtime toolchain in MODULE.bazel for centralized version management

This change eliminates duplicate wasmtime installation logic by registering
the wasmtime toolchain in MODULE.bazel and extracting it from Bazel's cache
in the performance workflow.

Changes:
- MODULE.bazel: Register wasmtime toolchain using rules_wasm_component extension
- performance.yml: Extract wasmtime from @wasmtime_toolchain instead of manual download
- Use bazel info output_base to construct full path to cached binary

Benefits:
- Single source of truth for wasmtime version (centralized in MODULE.bazel)
- Reuses Bazel's cached download (faster, no redundant network calls)
- Eliminates manual version maintenance in performance.yml
- Consistent wasmtime version across all Bazel builds and CI workflows

Author: avrabe

.github/workflows/performance.yml

@@ -70,25 +70,27 @@ jobs:
           brew install hyperfine
         fi
 
-        # Install wasmtime - use manual installation since @wasmtime toolchain not registered
-        # TODO: Register wasmtime toolchain in MODULE.bazel to reuse Bazel's download
-        if [[ "${{ matrix.os }}" == "ubuntu-latest" ]]; then
-          WASMTIME_VERSION="v27.0.0"
-          curl -L "https://github.com/bytecodealliance/wasmtime/releases/download/${WASMTIME_VERSION}/wasmtime-${WASMTIME_VERSION}-x86_64-linux.tar.xz" -o wasmtime.tar.xz
-          tar -xf wasmtime.tar.xz
-          sudo mv "wasmtime-${WASMTIME_VERSION}-x86_64-linux/wasmtime" /usr/local/bin/
-          rm -rf wasmtime.tar.xz "wasmtime-${WASMTIME_VERSION}-x86_64-linux"
-        elif [[ "${{ matrix.os }}" == "macos-latest" ]]; then
-          WASMTIME_VERSION="v27.0.0"
-          curl -L "https://github.com/bytecodealliance/wasmtime/releases/download/${WASMTIME_VERSION}/wasmtime-${WASMTIME_VERSION}-aarch64-macos.tar.xz" -o wasmtime.tar.xz
-          tar -xf wasmtime.tar.xz
-          sudo mv "wasmtime-${WASMTIME_VERSION}-aarch64-macos/wasmtime" /usr/local/bin/
-          rm -rf wasmtime.tar.xz "wasmtime-${WASMTIME_VERSION}-aarch64-macos"
+        # Use wasmtime from Bazel toolchain (registered in MODULE.bazel)
+        # This ensures version consistency and reuses Bazel's cached download
+        echo "Extracting wasmtime from Bazel toolchain..."
+
+        # Get Bazel output base and wasmtime relative path
+        OUTPUT_BASE=$(bazel info output_base 2>/dev/null)
+        WASMTIME_REL=$(bazel cquery --output=files @wasmtime_toolchain//:wasmtime 2>/dev/null | head -1)
+        WASMTIME_PATH="$OUTPUT_BASE/$WASMTIME_REL"
+
+        if [ -f "$WASMTIME_PATH" ]; then
+          echo "Found wasmtime at: $WASMTIME_PATH"
+          sudo cp "$WASMTIME_PATH" /usr/local/bin/wasmtime
+          sudo chmod +x /usr/local/bin/wasmtime
+          wasmtime --version
+        else
+          echo "Error: Could not find wasmtime binary from Bazel at: $WASMTIME_PATH"
+          echo "Output base: $OUTPUT_BASE"
+          echo "Relative path: $WASMTIME_REL"
+          exit 1
         fi
 
-        # Verify it works
-        wasmtime --version
-
     - name: Build All Components
       run: |
         # Build TinyGo component (regular version)

MODULE.bazel

@@ -83,6 +83,18 @@ register_toolchains(
     "@wasi_sdk//:cc_toolchain",
 )
 
+# Wasmtime runtime toolchain for running and testing WASM components
+wasmtime = use_extension("@rules_wasm_component//wasm:extensions.bzl", "wasmtime")
+wasmtime.register(
+    name = "wasmtime",
+    strategy = "download",
+    version = "35.0.0",  # Latest version with verified checksums
+)
+use_repo(wasmtime, "wasmtime_toolchain")
+
+# Register wasmtime toolchain
+register_toolchains("@wasmtime_toolchain//:wasmtime_toolchain")
+
 # Register C++ toolchains explicitly for cross-platform compatibility
 # This ensures Linux CI has proper C++ toolchain resolution for Rust binaries
 register_toolchains("@bazel_tools//tools/cpp:all")