fix(ci): restore wasm32v1-none target and remove WASM_BUILD_STD=0

The WASM_BUILD_STD=0 approach caused panic_impl duplicate errors because
wasm32-unknown-unknown pre-built sysroot includes std, conflicting with
pezsp-io's panic handler in wasm runtime builds.

Local testing confirmed that wasm32v1-none + no build-std + serde fork
works correctly. The wasm-builder creates a separate cargo project that:
- Excludes std/default features from the runtime
- Has no client crates in the dependency tree
- Properly uses the serde fork for target_os="none" handling

Restore rustup target add wasm32v1-none in all 14 CI build jobs and
remove all WASM_BUILD_STD=0 overrides.

.github/workflows/check-pezframe-omni-bencher.yml

@@ -26,7 +26,6 @@ jobs:
       RUST_BACKTRACE: "full"
       WASM_BUILD_NO_COLOR: 1
       WASM_BUILD_RUSTFLAGS: "-C debug-assertions"
-      WASM_BUILD_STD: "0"
       RUST_LOG: "frame_omni_bencher=info,pezkuwi_sdk_frame=info"
     timeout-minutes: 60
     container:
@@ -35,6 +34,9 @@ jobs:
       - name: Checkout
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
+      - name: Install wasm32v1-none target
+        run: rustup target add wasm32v1-none
+
       - name: Clean cargo cache to free disk space
         run: |
           cargo clean 2>/dev/null || true
@@ -83,11 +85,13 @@ jobs:
       PACKAGE_NAME: ${{ matrix.runtime.package }}
       FLAGS: ${{ matrix.runtime.bench_flags }}
       RUST_LOG: "frame_omni_bencher=info,pezkuwi_sdk_frame=info"
-      WASM_BUILD_STD: "0"
     steps:
       - name: Checkout
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
+      - name: Install wasm32v1-none target
+        run: rustup target add wasm32v1-none
+
       - name: script (benchmark ${{ matrix.bench_cmd }})
         id: required
         shell: bash