feat(cli): add config file support and content gate mode

[dev-pi2pie]

Summary

This PR adds first-class CLI config file support and related follow-up fixes, then updates repository automation to keep Node 22 CI/CD runs on the latest March 24, 2026 security patch release.

Changes

• add CLI config loading and normalization support for JSON, JSONC, and TOML config files
• add config discovery, environment input handling, source resolution, schema typing, merge behavior, and apply logic under src/cli/config/
• wire config precedence into command execution so CLI flags still override config values correctly
• add content gate mode support in config
• restore config path compatibility fallbacks
• restore expected flag precedence for recursive and progress modes
• update command, inspect, batch-runtime, doctor, and detector-related CLI flows to consume the new config layer
• add example config files under examples/wc-config/
• expand docs for config usage, schema expectations, doctor output, and related plan/research/job records
• expand automated coverage with new config-focused tests and follow-up regression tests
• keep the published package runtime contract at Node.js >=22.18.0
• update GitHub Actions workflow setup-node pins from 22.18.0 to 22.22.2 in CI and release jobs

Main Files Affected

• .github/workflows/ci.yml
• .github/workflows/release.yml
• README.md
• docs/config-usage-guide.md
• docs/schemas/default-config.md
• examples/wc-config/wc-intl-seg.config.json
• examples/wc-config/wc-intl-seg.config.jsonc
• examples/wc-config/wc-intl-seg.config.toml
• src/cli/config/
• src/command.ts
• test/cli-config.test.ts
• test/command-config.test.ts
• test/example-config-files.test.ts

Branch Delta Against main

Notable commits in this branch:

• feat(cli): add config parsing and discovery foundation
• feat(cli): wire config precedence and detector defaults
• feat(cli): complete config file support and docs
• feat(cli): add config support for content gate mode
• fix(cli): restore config path compatibility fallbacks
• fix(cli): restore flag precedence for recursive and progress modes
• ci(workflows): patch Node 22 CI/CD pins to 22.22.2

Suggested Validation

bun run type-check
bun test
bun run build
bun run verify:package-contents

Notes

• This PR intentionally does not raise package.json engines.node beyond >=22.18.0.
• The CI/CD Node pin update is operational hardening for repo automation, not a consumer runtime policy change.