feat: Anthropic web server tools, provider metadata, messaging hardening

- Add local web_search/web_fetch SSE handling and optional tool schemas
- Extend HeuristicToolParser for JSON-style WebFetch/WebSearch text
- Consolidate provider defaults, ids, and exception typing; stream contracts
- Messaging: typed options, voice config injection, platform contract cleanup
- Tests for web server tools, converters, parsers, contracts; ignore debug-*.log

api/__init__.py

@@ -1,7 +1,6 @@
 """API layer for Claude Code Proxy."""
 
 from .app import app, create_app
-from .dependencies import get_provider, get_provider_for_type
 from .models import (
     MessagesRequest,
     MessagesResponse,
@@ -16,6 +15,4 @@ __all__ = [
     "TokenCountResponse",
     "app",
     "create_app",
-    "get_provider",
-    "get_provider_for_type",
 ]