refactor: move model definitions into providers and extract resolve module

- Rename ImageProvider to BlackForestProvider, TextProvider to MistralProvider
- Add get_provided_models() abstract method to Provider base class
- Move model lists from models.py into each provider's get_provided_models()
- Add providers/registry.py to aggregate models from all providers
- Extract infer_required_capabilities and resolve_model from config.py to resolve.py
- Update tests to use new names and import paths

bulkgen/builder.py

@@ -12,14 +12,13 @@ from pathlib import Path
 from bulkgen.config import (
     ProjectConfig,
     TargetType,
-    infer_required_capabilities,
-    resolve_model,
     target_type_from_capabilities,
 )
 from bulkgen.graph import build_graph, get_build_order, get_subgraph_for_target
 from bulkgen.providers import Provider
-from bulkgen.providers.image import ImageProvider
-from bulkgen.providers.text import TextProvider
+from bulkgen.providers.blackforest import BlackForestProvider
+from bulkgen.providers.mistral import MistralProvider
+from bulkgen.resolve import infer_required_capabilities, resolve_model
 from bulkgen.state import (
     BuildState,
     is_target_dirty,
@@ -106,10 +105,10 @@ def _create_providers() -> dict[TargetType, Provider]:
     providers: dict[TargetType, Provider] = {}
     bfl_key = os.environ.get("BFL_API_KEY", "")
     if bfl_key:
-        providers[TargetType.IMAGE] = ImageProvider(api_key=bfl_key)
+        providers[TargetType.IMAGE] = BlackForestProvider(api_key=bfl_key)
     mistral_key = os.environ.get("MISTRAL_API_KEY", "")
     if mistral_key:
-        providers[TargetType.TEXT] = TextProvider(api_key=mistral_key)
+        providers[TargetType.TEXT] = MistralProvider(api_key=mistral_key)
     return providers