feat: remove direct OpenSSL dependency, use OS-native TLS

Remove the explicit openssl crate dependency and actix-web's openssl
feature. TLS is now controlled via two mutually exclusive features:

- native-tls (default): uses the OS-native TLS stack (OpenSSL on Linux,
  Secure Transport on macOS, SChannel on Windows)
- rustls: pure-Rust TLS, used for musl targets that lack a system TLS

This eliminates the vendored feature, the vcpkg/OpenSSL setup in CI for
Windows builds, and reduces the dependency tree significantly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ctron

.github/workflows/ci.yaml

@@ -43,34 +43,12 @@ jobs:
           - os: ubuntu-latest
             install: |
               sudo apt install -y libssl-dev
-          - os: windows-latest
-            install: |
-              echo "VCPKG_ROOT=$env:VCPKG_INSTALLATION_ROOT" | Out-File -FilePath $env:GITHUB_ENV -Append
-              vcpkg install openssl:x64-windows-static-md
 
     runs-on: ${{ matrix.os }}
 
     steps:
       - uses: actions/checkout@v7
 
-      - name: Configure vcpkg binary cache
-        if: runner.os == 'Windows'
-        shell: bash
-        run: |
-          cache_dir="${{ runner.temp }}/vcpkg-binary-cache"
-          mkdir -p "$cache_dir"
-          echo "VCPKG_DEFAULT_BINARY_CACHE=$cache_dir" >> "$GITHUB_ENV"
-          echo "VCPKG_BINARY_SOURCES=clear;files,$cache_dir,readwrite" >> "$GITHUB_ENV"
-
-      - name: Cache vcpkg binaries
-        uses: actions/cache@v6
-        if: runner.os == 'Windows'
-        with:
-          path: ${{ runner.temp }}/vcpkg-binary-cache
-          key: ${{ runner.os }}-vcpkg-${{ matrix.rust }}-${{ hashFiles('.github/workflows/ci.yaml') }}
-          restore-keys: |
-            ${{ runner.os }}-vcpkg-${{ matrix.rust }}-
-
       - uses: Swatinem/rust-cache@v2
         with:
           shared-key: ${{ matrix.rust }}
@@ -85,6 +63,7 @@ jobs:
           rustup toolchain install ${{ matrix.rust }} --component clippy
 
       - name: Install dependencies
+        if: matrix.install
         run: ${{ matrix.install }}
 
       - name: Check

.github/workflows/release.yaml

@@ -77,28 +77,23 @@ jobs:
 
           - target: aarch64-unknown-linux-musl
             os: ubuntu-22.04-arm
+            args: --no-default-features --features rustls
             install: |
               sudo apt install -y musl-tools
-            args: --features vendored
           - target: x86_64-unknown-linux-musl
             os: ubuntu-22.04
+            args: --no-default-features --features rustls
             install: |
               sudo apt install -y musl-tools
-            args: --features vendored
 
           - target: x86_64-apple-darwin
             os: macos-15-intel
-            args: --features vendored
           - target: aarch64-apple-darwin
             os: macos-15
-            args: --features vendored
 
           - target: x86_64-pc-windows-msvc
             os: windows-2022
             exe: ".exe"
-            install: |
-              echo "VCPKG_ROOT=$env:VCPKG_INSTALLATION_ROOT" | Out-File -FilePath $env:GITHUB_ENV -Append
-              vcpkg install openssl:x64-windows-static-md
           - target: aarch64-pc-windows-msvc
             os: windows-11-arm
             exe: ".exe"
@@ -107,9 +102,6 @@ jobs:
               Start-Process -FilePath .\rustup-init.exe -ArgumentList "-y" -NoNewWindow -Wait
               echo "$env:USERPROFILE\.cargo\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
 
-              echo "VCPKG_ROOT=$env:VCPKG_INSTALLATION_ROOT" | Out-File -FilePath $env:GITHUB_ENV -Append
-              vcpkg install openssl:arm64-windows-static-md
-
     runs-on: ${{ matrix.os }}
 
     steps:
@@ -118,24 +110,6 @@ jobs:
         with:
           fetch-depth: 0
 
-      - name: Configure vcpkg binary cache
-        if: runner.os == 'Windows'
-        shell: bash
-        run: |
-          cache_dir="${{ runner.temp }}/vcpkg-binary-cache"
-          mkdir -p "$cache_dir"
-          echo "VCPKG_DEFAULT_BINARY_CACHE=$cache_dir" >> "$GITHUB_ENV"
-          echo "VCPKG_BINARY_SOURCES=clear;files,$cache_dir,readwrite" >> "$GITHUB_ENV"
-
-      - name: Cache vcpkg binaries
-        uses: actions/cache@v6
-        if: runner.os == 'Windows'
-        with:
-          path: ${{ runner.temp }}/vcpkg-binary-cache
-          key: ${{ runner.os }}-vcpkg-${{ matrix.target }}-${{ hashFiles('.github/workflows/release.yaml') }}
-          restore-keys: |
-            ${{ runner.os }}-vcpkg-${{ matrix.target }}-
-
       - uses: Swatinem/rust-cache@v2
         with:
           shared-key: ${{ matrix.target }}