feat: integrate Pollinations AI enhancements and simplify gpt4free references

- Replaced the large GitHub project stats table in `README.md` with summaries and logos for Pollinations AI and MoneyPrinter V2
- Introduced `STATIC_URL` and `DIST_DIR` constants in new `g4f/constants.py` and used them across multiple files
- Updated `PollinationsAI.py` to support conversation title and follow-up generation using tool calls
- Modified `PollinationsAI.py` and `PollinationsImage.py` to use `STATIC_URL` for the `referrer` header
- Enhanced `PollinationsAI.stream_complete` to yield `ToolCalls`, `TitleGeneration`, and `SuggestedFollowups`
- Added `ToolCalls` handling in `client/__init__.py` to support non-stream and stream modes
- Updated `ChatCompletionDelta` model in `client/stubs.py` to support `ToolCalls`
- Modified `HarProvider` to merge `DEFAULT_HEADERS` into request headers
- Improved `OpenaiChat.py` by adding optional chaining to page evaluation expressions for robustness
- Updated `any_provider.py` to force use of `PollinationsAI` if `tools` key is present in kwargs
- Refactored `is_content` into a reusable function in `providers/response.py` and used in `retry_provider.py`
- Updated `gui/server/website.py` to use `STATIC_URL` and simplify `GPT4FREE_URL` handling
- Removed redundant constants from `version.py` and imported them from `constants.py

g4f/providers/any_provider.py

@@ -221,7 +221,9 @@ class AnyProvider(AsyncGeneratorProvider, ProviderModelMixin):
                         has_audio = True
                         break
                     has_image = True
-            if "audio" in kwargs or "audio" in kwargs.get("modalities", []):
+            if "tools" in kwargs:
+                providers = [PollinationsAI]
+            elif "audio" in kwargs or "audio" in kwargs.get("modalities", []):
                 providers = [PollinationsAI, EdgeTTS, gTTS]
             elif has_audio:
                 providers = [PollinationsAI, Microsoft_Phi_4_Multimodal, MarkItDown]