feat: configure gRPC UNIX socket attributes

[rustatian]

Part of roadrunner-server/roadrunner#1789.

• Add grpc.unix_socket settings for mode, UID, and GID.
• Use tcplisten v1.6.0 and its shared schema. Omitted settings keep the current defaults.
• Validate typed socket options after configuration decoding.
• Pass socket attributes to the gRPC listener without changing TLS or worker credentials.

Explicit socket attributes require a filesystem UNIX listener.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.47%. Comparing base (4965bf6) to head (682eef9).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #154      +/-   ##
==========================================
+ Coverage   84.81%   85.47%   +0.65%     
==========================================
  Files          10       10              
  Lines         652      654       +2     
==========================================
+ Hits          553      559       +6     
+ Misses         99       95       -4     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Copilot]

🟡 Changes recommended

The new UID/GID string validation is architecture-dependent (32-bit vs 64-bit) and can incorrectly reject valid IDs due to strconv.IntSize parsing.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR adds configurable UNIX socket attributes (mode/UID/GID) for the gRPC listener by upgrading to tcplisten v1.6.0, wiring the options into listener creation, and extending the JSON schema and tests to cover validation and serving behavior.

Changes:

• Add grpc.unix_socket to config/schema and pass options into tcplisten.CreateListenerWithOptions.
• Add strict validation for uid/gid inputs to reject weak/ambiguous decodings.
• Add a new OS-gated test suite validating config decoding, ID validation, and actual socket attributes during Serve.

File summaries

File	Description
tests/unix_socket_test.go	Adds coverage for unix_socket config decoding, UID/GID validation edge cases, and runtime socket attribute application.
config.go	Introduces UnixSocket config field, validates unix_socket against the listen address, and adds strict UID/GID validation helper.
plugin.go	Validates unix_socket ID inputs (when present) and passes unix socket options into listener creation.
schema.json	Exposes unix_socket settings by referencing the shared tcplisten schema.
go.mod	Bumps github.com/roadrunner-server/tcplisten to v1.6.0.
go.sum	Updates checksums for tcplisten v1.6.0.
tests/go.mod	Bumps test module’s tcplisten dependency to v1.6.0.
tests/go.sum	Updates test module checksums for tcplisten v1.6.0.

Review details

• Files reviewed: 6/8 changed files
• Comments generated: 1
• Review effort level: Lite

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.