Part of kcenon/common_system#454

What

Add grpc (1.51.1) and protobuf (3.21.12) version overrides to vcpkg.json. database_system uses grpc/protobuf in its ecosystem feature (via monitoring_system and logger_system dependencies) but does not pin their versions, unlike all peer systems that reference these packages.

• Current: overrides contains asio, openssl, libpq, libpqxx, sqlite3, mongo-cxx-driver, hiredis, spdlog, gtest, benchmark — no grpc or protobuf
• Expected: overrides also includes grpc 1.51.1 and protobuf 3.21.12
• Scope: vcpkg.json overrides section only

Why

• database_system's ecosystem feature enables monitoring_system and logger_system integration, both of which depend on grpc/protobuf
• logger_system, container_system, monitoring_system, and network_system all pin grpc to 1.51.1 and protobuf to 3.21.12
• Without overrides, building database_system with the ecosystem feature may resolve different grpc/protobuf versions than peer systems
• Ecosystem standard defined in DEPENDENCY_MATRIX.md: grpc 1.51.1, protobuf 3.21.12

Where

• vcpkg.json overrides array (currently 10 entries, add 2 more)

How

Technical Approach

Add two entries to the overrides array:

{ "name": "grpc", "version": "1.51.1" },
{ "name": "protobuf", "version": "3.21.12" }

Acceptance Criteria

• grpc override at version 1.51.1 is present in vcpkg.json
• protobuf override at version 3.21.12 is present in vcpkg.json
• Existing overrides are unchanged
• vcpkg install with ecosystem feature resolves without version conflict warnings