File‑Based Configuration System with Hot Reload

[viksachdev]

Introduce a validated, file‑based configuration system that enables dynamic, configuration‑driven filter chains (enable/disable and parameterize filters without code changes), with hot reload, deterministic precedence, and safe rollout.

Scope

• Config sources: YAML/JSON files with env substitution.
• Deterministic discovery: --config > MCP_CONFIG > ./config/ > /etc/gopher-mcp/ with config.d/*.yaml overlays (lex order).
• Filter ordering model: stages security → QoS → observability → protocol → application; constraints requires|before|after.
• Hot reload: platform watcher