fix(ci): gate config assistant Go tests

[LeXwDeX]

Description\n\nThe repository contains a standalone Go module under config_assistant with unit tests, but the full CI workflow runs only Bun/Turbo, generated-artifact checks, HttpAPI gates, and Playwright. Go regressions can therefore merge while the advertised full test suite remains green.\n\nSeverity: HIGH (release blocker).\n\n## Reproduce\n\n1. Introduce a failing test under config_assistant.\n2. Run the current ci-test workflow.\n3. No job executes go test ./....\n\n## Acceptance\n\n- Full CI installs a pinned Go toolchain and runs go test ./... in config_assistant.\n- The command is part of the main release gate.\n- Workflow documentation lists the Go suite.\n

[LeXwDeX]

已由 PR #148 修复，并通过 PR #149 晋级 main。config_assistant 的 go test ./... 已纳入 Linux Unit CI，dev/main 门禁均通过。