refactor(commands): modularize artifact workflow into separate files (#562)

* refactor(commands): modularize artifact workflow into separate files

Split the monolithic artifact-workflow.ts into separate modules under
src/commands/experimental/:
- index.ts: main exports and command registration
- status.ts: status display logic
- new-change.ts: change creation logic
- schemas.ts: Zod schemas
- setup.ts: setup command logic
- templates.ts: template generation
- shared.ts: shared utilities
- instructions.ts: instruction generation

Also extracted init wizard logic to src/core/init/wizard.ts.

* fix(commands): address code review feedback from PR #562

- Fix template source detection using path.relative instead of startsWith
  to prevent misclassification of paths with shared prefixes
- Fix config file log message to show actual file name (config.yaml vs config.yml)
- Fix selectedTools option to be honored when provided programmatically

Author: TabishB

src/cli/index.ts

@@ -15,7 +15,7 @@ import { ShowCommand } from '../commands/show.js';
 import { CompletionCommand } from '../commands/completion.js';
 import { FeedbackCommand } from '../commands/feedback.js';
 import { registerConfigCommand } from '../commands/config.js';
-import { registerArtifactWorkflowCommands } from '../commands/artifact-workflow.js';
+import { registerArtifactWorkflowCommands } from '../commands/experimental/index.js';
 import { registerSchemaCommand } from '../commands/schema.js';
 import { maybeShowTelemetryNotice, trackCommand, shutdown } from '../telemetry/index.js';