feat: live HubClient with generated proto bindings

Proto codegen wired in. tools/generate.sh wraps protoc against
../fai_platform/proto/, including the well-known types (Empty,
Struct, Timestamp) so they are generated alongside fai's own
messages — protobuf 4.x doesn't ship them as importable Dart
types, so we have to generate them ourselves.

HubClient now exposes typed methods backed by real RPCs:
- healthy() — Hub.Health probe (returns false on connect refused).
- listCapabilities() — HubAdmin.ListCapabilities.
- eventLog() — HubAdmin.EventLog with type filter.
- listApprovals() — HubAdmin.ListApprovals (status filter).
- approve() / reject() — HubAdmin.DecideApproval.

Generated bindings under lib/src/generated/ are excluded from
analyze (out of our style control). protoc_plugin pinned to
22.2.0 in tools/generate.sh comment because newer plugins
generate code against protobuf 6.x, while grpc 4.x still
constrains us to protobuf 4.x.

Bumps fai_dart_sdk 0.1.0 -> 0.2.0.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

tools/generate.sh

@@ -0,0 +1,97 @@
+#!/usr/bin/env bash
+# Generate Dart bindings for the F∆I gRPC surface.
+#
+# Reads .proto files from the sibling fai_platform repo and
+# writes Dart code into lib/src/generated/. Run after
+# `dart pub global activate protoc_plugin` so that
+# `protoc-gen-dart` is on PATH (`$HOME/.pub-cache/bin`).
+#
+# Usage:
+#   tools/generate.sh
+#
+# Env overrides:
+#   PROTO_ROOT   Path to fai_platform/proto/ (default: ../fai_platform/proto)
+#   OUT_DIR      Output dir (default: lib/src/generated)
+set -euo pipefail
+
+SCRIPT_DIR="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+SDK_ROOT="$( cd -- "$SCRIPT_DIR/.." && pwd )"
+
+PROTO_ROOT="${PROTO_ROOT:-$SDK_ROOT/../fai_platform/proto}"
+OUT_DIR="${OUT_DIR:-$SDK_ROOT/lib/src/generated}"
+
+if [[ ! -d "$PROTO_ROOT" ]]; then
+  echo "error: PROTO_ROOT does not exist: $PROTO_ROOT" >&2
+  echo "Set PROTO_ROOT to the fai_platform/proto directory." >&2
+  exit 1
+fi
+
+if ! command -v protoc >/dev/null 2>&1; then
+  echo "error: protoc not found on PATH" >&2
+  echo "Install: brew install protobuf  (macOS)" >&2
+  exit 1
+fi
+
+# Make sure protoc-gen-dart is reachable. pub-cache/bin is the
+# canonical location after `dart pub global activate protoc_plugin`.
+export PATH="$HOME/.pub-cache/bin:$PATH"
+if ! command -v protoc-gen-dart >/dev/null 2>&1; then
+  echo "error: protoc-gen-dart not found" >&2
+  echo "Install: dart pub global activate protoc_plugin" >&2
+  exit 1
+fi
+
+mkdir -p "$OUT_DIR"
+
+# Find every proto file under the package root and pass them to
+# protoc with --dart_out for messages and grpc=true for services.
+PROTO_FILES=()
+while IFS= read -r -d '' file; do
+  PROTO_FILES+=("$file")
+done < <(find "$PROTO_ROOT" -name '*.proto' -print0)
+
+if [[ ${#PROTO_FILES[@]} -eq 0 ]]; then
+  echo "error: no .proto files found under $PROTO_ROOT" >&2
+  exit 1
+fi
+
+# Locate the well-known-types include directory. Required so we
+# can generate Dart bindings for google.protobuf.Empty,
+# google.protobuf.Struct, etc. that the platform's protos import.
+WKT_INCLUDE=""
+for candidate in \
+  "/opt/homebrew/include" \
+  "/usr/local/include" \
+  "/usr/include"; do
+  if [[ -f "$candidate/google/protobuf/empty.proto" ]]; then
+    WKT_INCLUDE="$candidate"
+    break
+  fi
+done
+
+if [[ -z "$WKT_INCLUDE" ]]; then
+  echo "error: google/protobuf/empty.proto not found in standard include dirs" >&2
+  echo "Install protobuf (brew install protobuf) so the well-known types ship alongside protoc." >&2
+  exit 1
+fi
+
+WKT_PROTOS=(
+  "$WKT_INCLUDE/google/protobuf/empty.proto"
+  "$WKT_INCLUDE/google/protobuf/struct.proto"
+  "$WKT_INCLUDE/google/protobuf/timestamp.proto"
+)
+
+echo "generating Dart bindings"
+echo "  protos: ${#PROTO_FILES[@]} files under $PROTO_ROOT"
+echo "  WKT include: $WKT_INCLUDE"
+echo "  output: $OUT_DIR"
+
+protoc \
+  --proto_path="$PROTO_ROOT" \
+  --proto_path="$WKT_INCLUDE" \
+  --dart_out=grpc:"$OUT_DIR" \
+  "${PROTO_FILES[@]}" \
+  "${WKT_PROTOS[@]}"
+
+echo "done. generated files:"
+find "$OUT_DIR" -name '*.dart' | sort