feat(config): accept autofix settings in project manifests

[marckong]

Tracking

None. Follow-up to the OpenAPI sync in #51, whose AI review flagged this (client.gen.go:8598).

Why

The synced contract adds autofix to ProjectConfig, so volcano config pull can export an autofix: section. Manifest decodes with KnownFields(true) and has no such field, so the CLI could not load its own pulled manifest.

Summary

• Add AutofixManifest (enabled, auto_trigger, max_stage, model, provider) to Manifest. Nil fields preserve current values; enum values stay server-validated.
• The API key is deliberately not a manifest field.
• Document the section in docs/project-configuration.md.

Verification

• go test ./internal/projectconfig/ ./internal/cmd/config/ ./internal/docs/... pass, including new round-trip, omitted-vs-explicit-false, and api_key-rejected cases.
• go vet and gofmt clean. Full make check and the docs lint were not run locally.

🤖 Generated with Claude Code

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