feat(wfe-server): gRPC reflection, auto-generated schema endpoints, Dockerfile

- tonic-reflection for gRPC service discovery
  - /schema/workflow.json (JSON Schema from schemars derives)
  - /schema/workflow.yaml (same schema in YAML)
  - /schema/workflow.proto (raw proto file)
  - Multi-stage alpine Dockerfile with all executor features
  - Comprehensive configuration reference (wfe-server/README.md)
  - Release script (scripts/release.sh)
  - Bumped to 1.8.1

wfe-server-protos/build.rs

@@ -1,12 +1,18 @@
+use std::path::PathBuf;
+
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let proto_files = vec!["proto/wfe/v1/wfe.proto"];
 
+    let out_dir = PathBuf::from(std::env::var("OUT_DIR")?);
+    let descriptor_path = out_dir.join("wfe_descriptor.bin");
+
     let mut prost_config = prost_build::Config::new();
     prost_config.include_file("mod.rs");
 
     tonic_prost_build::configure()
         .build_server(true)
         .build_client(true)
+        .file_descriptor_set_path(&descriptor_path)
         .compile_with_config(
             prost_config,
             &proto_files,