docs(python-sdk): add pre-release notice and source installation instructions

Author: Patel230

README.md

@@ -29,9 +29,23 @@ the same API surface on each.
 
 ## Installation
 
-```bash
-pip install hawk-sdk
-```
+> **⚠️ Pre-release — not yet published to PyPI.**
+>
+> `hawk-sdk` is under active development and has not yet been published to
+> the Python Package Index. Installing from PyPI will fail until a stable
+> release is tagged. In the meantime, install directly from source:
+>
+> ```bash
+> git clone https://github.com/GrayCodeAI/hawk-sdk-python.git
+> cd hawk-sdk-python
+> pip install -e .
+> ```
+>
+> Once the first stable release is tagged, the standard install will work:
+>
+> ```bash
+> pip install hawk-sdk   # available after first stable release
+> ```
 
 ## Quick Start