ci: install protoc in CI + release runners

lance-encoding uses prost-build, which needs a system protoc at build
time. Both workflows now install it before toolchain setup:

  ci.yml        → apt-get install protobuf-compiler (Ubuntu runner)
  release.yml   → conditional step: apt on Linux, brew on macOS;
                  matches each matrix target's runner.os

Without this, cargo clippy / cargo build fails with
  "Could not find `protoc`. … To install it on Debian, run
   `apt-get install protobuf-compiler`."
(CI run 24740454924).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: linggen

.github/workflows/ci.yml

@@ -16,6 +16,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: install protoc
+        # lance-encoding (via lancedb) uses prost-build and needs protoc.
+        run: sudo apt-get update && sudo apt-get install -y protobuf-compiler
+
       - uses: dtolnay/rust-toolchain@stable
         with:
           components: clippy, rustfmt

.github/workflows/release.yml

@@ -33,6 +33,14 @@ jobs:
         with:
           ref: ${{ github.event.inputs.tag || github.ref }}
 
+      - name: install protoc (Linux)
+        if: runner.os == 'Linux'
+        run: sudo apt-get update && sudo apt-get install -y protobuf-compiler
+
+      - name: install protoc (macOS)
+        if: runner.os == 'macOS'
+        run: brew install protobuf
+
       - uses: dtolnay/rust-toolchain@stable
         with:
           targets: ${{ matrix.target }}