Replace dotnet proto build with Bazel-hermetic C# proto generation (#6097)

* Replace dotnet proto build with Bazel-hermetic C# proto generation

Use rules_proto_grpc_csharp to generate .cs source files via Bazel
instead of requiring a locally-installed dotnet SDK to build protos.dll.
This eliminates the dotnet dependency for CI runners and makes the
proto build fully hermetic.

- Add bazel_dep for rules_proto_grpc_csharp 5.8.0
- Bump grpc 1.74.0 -> 1.74.1 (required by rules_proto_grpc_csharp)
- Add csharp_proto_compile/csharp_grpc_compile targets across 8 proto
  BUILD.bazel files (81 .cs files from 78 protos)
- Rewrite build_protos.sh to use bazel build + copy instead of dotnet
- Output goes to Assets/GeneratedProtos/ with package-based subdirs
  to avoid filename collisions (e.g. ActionResultView.cs in both
  shardok/api/ and eagle/views/)
- Add Assets/GeneratedProtos/ to .gitignore

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

* Remove stale Eagle0Protos DLL references

The old build_protos.sh generated protos.dll via dotnet; the new one
generates .cs source files instead. Remove the tracked .meta and
.deps.json files that reference the no-longer-generated DLL, and
gitignore the directory to prevent re-adding.

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

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

scripts/build_protos.sh

@@ -2,7 +2,57 @@
 
 set -euxo pipefail
 
-/bin/echo "build protos"
-mkdir -p src/main/csharp/net/eagle0/clients/unity/eagle0/Assets/Plugins/Eagle0Protos/
-dotnet build src/main/csharp/net/eagle0/clients/unity/eagle0/protos/protos.csproj \
-    -o src/main/csharp/net/eagle0/clients/unity/eagle0/Assets/Plugins/Eagle0Protos/
+REPO_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+UNITY_ROOT="$REPO_ROOT/src/main/csharp/net/eagle0/clients/unity/eagle0"
+OUTPUT_DIR="$UNITY_ROOT/Assets/GeneratedProtos"
+
+# All C# protobuf generation targets
+TARGETS=(
+    "//src/main/protobuf/net/eagle0/common:common_csharp_proto_srcs"
+    "//src/main/protobuf/net/eagle0/shardok/storage:storage_csharp_proto_srcs"
+    "//src/main/protobuf/net/eagle0/shardok/common:common_csharp_proto_srcs"
+    "//src/main/protobuf/net/eagle0/shardok/api:api_csharp_proto_srcs"
+    "//src/main/protobuf/net/eagle0/eagle/common:common_csharp_proto_srcs"
+    "//src/main/protobuf/net/eagle0/eagle/views:views_csharp_proto_srcs"
+    "//src/main/protobuf/net/eagle0/eagle/api:api_csharp_proto_srcs"
+    "//src/main/protobuf/net/eagle0/eagle/api:api_csharp_grpc_srcs"
+    "//src/main/protobuf/net/eagle0/eagle/api/command/util:util_csharp_proto_srcs"
+)
+
+# Subdirectory for each target (avoids filename collisions across packages)
+SUBDIRS=(
+    "net/eagle0/common"
+    "net/eagle0/shardok/storage"
+    "net/eagle0/shardok/common"
+    "net/eagle0/shardok/api"
+    "net/eagle0/eagle/common"
+    "net/eagle0/eagle/views"
+    "net/eagle0/eagle/api"
+    "net/eagle0/eagle/api"
+    "net/eagle0/eagle/api/command/util"
+)
+
+/bin/echo "Building C# protobuf sources..."
+bazel build "${TARGETS[@]}"
+
+/bin/echo "Copying generated .cs files to $OUTPUT_DIR..."
+rm -rf "$OUTPUT_DIR"
+
+for i in "${!TARGETS[@]}"; do
+    target="${TARGETS[$i]}"
+    subdir="${SUBDIRS[$i]}"
+
+    # Convert target label to bazel-bin path
+    # //src/main/protobuf/net/eagle0/common:common_csharp_proto_srcs
+    # -> bazel-bin/src/main/protobuf/net/eagle0/common/common_csharp_proto_srcs
+    target_path="${target#//}"
+    pkg="${target_path%%:*}"
+    name="${target_path##*:}"
+    bin_dir="$REPO_ROOT/bazel-bin/$pkg/$name"
+
+    dest_dir="$OUTPUT_DIR/$subdir"
+    mkdir -p "$dest_dir"
+    find "$bin_dir" -name "*.cs" -exec cp {} "$dest_dir/" \;
+done
+
+/bin/echo "Done. Generated C# proto sources in $OUTPUT_DIR"