refactor(ai): componentize runtime and configuration with schema-validated loading

[stringl1l1l1l]

This PR restructures the AI module around a component-based runtime, adds schema-driven configuration loading/validation, and aligns test coverage with the new architecture.

What Changed

1. Architecture refactor

• Migrated AI domains into ai/component/* and unified startup through a factory-based runtime.
• Standardized component lifecycle orchestration (Validate -> Init -> Start).

2. Configuration system upgrade

• Added a schema-aware loader with strict YAML decoding and JSON Schema validation.
• Added schema assets under ai/schema/json and unified component config entrypoints via ai/config.yaml.

3. CLI and workflow alignment

• Added/updated indexing CLI flow to use the new config/component model.
• Updated environment/config conventions (including SCHEMA_DIR and provider key usage).

4. Test consolidation

• Reorganized and expanded tests for config loader, runtime orchestration, component validation, and key workflows.

Breaking Changes

• Startup is now config-driven (-config, default config.yaml) rather than legacy server flags.
• Config files are strictly validated; unknown or structurally invalid fields now fail fast.
• Component YAML locations and wiring are now expected via ai/config.yaml.

Validation

go test -race -v ./config/... ./runtime/... ./component/... ./test/... ./cmd/...

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud