Vendor protoc for sqlite watcher

PR_BODY.md

@@ -1,7 +1,7 @@
 ## Summary
-- fix sqlite sync change-state handling by treating watcher wal_frame/cursor fields as optional strings and cleaning up unused code
-- implement FromStr for sqlite ChangeOperation and resolve needless borrow lints in queue/server modules
-- keep clippy happy by applying the suggested clamp change and ensuring proto tests build
+- vendor `protoc` via `protoc-bin-vendored` so sqlite-watcher can build on runners without system protobuf
+- update build script to set `PROTOC` before invoking `tonic_build`
+- refresh Cargo.lock to capture the new dependencies
 
 ## Testing
 - cargo clippy

sqlite-watcher/Cargo.toml

@@ -10,6 +10,7 @@ build = "build.rs"
 
 [build-dependencies]
 tonic-build = "0.11"
+protoc-bin-vendored = "3"
 
 [dependencies]
 anyhow = "1.0"

sqlite-watcher/build.rs

@@ -1,4 +1,6 @@
 fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let protoc = protoc_bin_vendored::protoc_bin_path()?;
+    std::env::set_var("PROTOC", protoc);
     tonic_build::configure()
         .build_client(true)
         .build_server(true)