Move aarch64 rustflags to .cargo/config.toml

- Add .cargo/config.toml with fp16 target feature for aarch64
- Remove RUSTFLAGS from CI workflows (now handled by cargo config)
- Update README to reflect the change

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: juntao

.cargo/config.toml

@@ -0,0 +1,2 @@
+[target.aarch64-unknown-linux-gnu]
+rustflags = ["-C", "target-feature=+fp16"]

.github/workflows/release.yml

@@ -108,7 +108,6 @@ jobs:
           CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER: aarch64-linux-gnu-gcc
           PKG_CONFIG_ALLOW_CROSS: "1"
           PKG_CONFIG_PATH: /usr/lib/aarch64-linux-gnu/pkgconfig
-          RUSTFLAGS: "-C target-feature=+fp16"
         run: cargo build --release --target aarch64-unknown-linux-gnu
 
       - name: Package release artifact

.github/workflows/rust_ci.yml

@@ -84,5 +84,4 @@ jobs:
           CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER: aarch64-linux-gnu-gcc
           PKG_CONFIG_ALLOW_CROSS: "1"
           PKG_CONFIG_PATH: /usr/lib/aarch64-linux-gnu/pkgconfig
-          RUSTFLAGS: "-C target-feature=+fp16"
         run: cargo build --release --target aarch64-unknown-linux-gnu

README.md

@@ -59,7 +59,7 @@ Edit `config.toml` to customize the VAD, ASR, LLM, TTS services, as well as prom
 cargo build --release
 ```
 
-**Note for aarch64 (ARM64) builds:** If building on or for aarch64 Linux, you may need to enable the fp16 target feature:
+**Note for aarch64 (ARM64) builds:** When cross-compiling for aarch64, the required `fp16` target feature is automatically enabled via `.cargo/config.toml`. If building natively on aarch64, you may need to set:
 
 ```
 RUSTFLAGS="-C target-feature=+fp16" cargo build --release