docs: reconcile env-variable semantics and server config docs with implementation

[Copilot]

Bug Fix

What was the bug?

Nightly reconciliation found multiple doc/implementation mismatches: MCP_GATEWAY_PORT/DOMAIN/API_KEY were documented as automatic config overrides (they are not), tool_response_filters was undocumented, and contributor/example docs were missing or inaccurate in a few high-impact spots.

How did you fix it?

• Environment variable behavior clarified (AGENTS.md)

  • Updated MCP_GATEWAY_PORT, MCP_GATEWAY_DOMAIN, and MCP_GATEWAY_API_KEY descriptions to match actual runtime behavior (validation/container checks vs. automatic gateway field override).
  • Clarified MCP_GATEWAY_PORT vs plain PORT semantics in the note at the end of the environment variable section.

• Missing server field documentation added (docs/CONFIGURATION.md)

  • Added tool_response_filters under server configuration fields.
  • Documented expected shape (map[toolName]jqExpression) and startup validation behavior for jq expressions.

• Configuration example coverage expanded (config.example.toml)

  • Added commented examples for:
    • tool_response_filters
    • connect_timeout
    • per-server tool_timeout
    • rate_limit_threshold
    • rate_limit_cooldown
    • HTTP auth (github-oidc)
    • working_directory
    • registry

• Contributor docs corrected (CONTRIBUTING.md)

  • Added missing direct dependency github.com/spf13/pflag.
  • Corrected project tree root label from awmg/ to gh-aw-mcpg/.

Testing

Docs-only change; no production logic changes.

# Example now documented in config.example.toml
[servers.github.tool_response_filters]
search_code = ".results[:20]"
get_file_contents = "{path: .path, sha: .sha}"

[Copilot]

Pull request overview

Updates documentation and examples to align gateway configuration semantics with the actual implementation, adding missing server config fields and correcting contributor guidance.

Changes:

• Document tool_response_filters in docs/CONFIGURATION.md (shape + startup validation behavior).
• Expand config.example.toml with commented examples for additional server fields (filters, timeouts, rate limiting, auth, etc.).
• Clarify env-var semantics in AGENTS.md and adjust contributor docs in CONTRIBUTING.md.

Show a summary per file

File	Description
docs/CONFIGURATION.md	Adds documentation for tool_response_filters under server configuration fields.
CONTRIBUTING.md	Corrects the project tree root label and adds github.com/spf13/pflag to the dependency list.
config.example.toml	Adds commented configuration examples for additional per-server fields (filters/timeouts/rate-limits/auth/registry/working_directory).
AGENTS.md	Updates env-var descriptions to reflect validation/container-check semantics rather than automatic config overrides.

Copilot's findings

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Comments suppressed due to low confidence (1)

AGENTS.md:406

• This note says run.sh uses plain PORT/HOST/MODE, but the script actually prefers MCP_GATEWAY_PORT when set (and container entrypoint uses MCP_GATEWAY_PORT as well). Updating the note to mention MCP_GATEWAY_PORT in the shell entrypoints would prevent confusion about which env var controls the bind port when running via scripts.

**Note:** `MCP_GATEWAY_PORT` is read by the `awmg` binary for environment validation (`--validate-env`) only. Plain `PORT`, `HOST`, and `MODE` are not read by `awmg` directly. However, `run.sh` uses `PORT`, `HOST` (default: `0.0.0.0`), and `MODE` (default: `--routed`) to set the bind address and routing mode. Use the `--listen` and `--routed`/`--unified` flags when running `awmg` directly.

• Files reviewed: 4/4 changed files
• Comments generated: 1