docs: Major README improvements based on comprehensive review

- Add Prerequisites section for clearer setup requirements
- Add Linux support with configuration paths and examples
- Add chmod +x instruction for script execution permissions
- Add comprehensive Troubleshooting section for common issues
- Add How It Works section explaining the architecture
- Improve run_gemini.sh to handle virtual environment gracefully
- Add absolute path examples for all operating systems
- Clarify error handling for Google safety filters

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

run_gemini.sh

@@ -3,6 +3,17 @@
 # Get the directory where this script is located
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 
-# Activate the virtual environment and run the server
-source "$SCRIPT_DIR/venv/bin/activate"
-python "$SCRIPT_DIR/gemini_server.py"
+# Check if virtual environment exists
+if [ -d "$SCRIPT_DIR/venv" ]; then
+    # Activate virtual environment
+    source "$SCRIPT_DIR/venv/bin/activate"
+    PYTHON_EXEC="python"
+else
+    # Fallback to system Python if venv doesn't exist
+    echo "Warning: Virtual environment not found at $SCRIPT_DIR/venv" >&2
+    echo "Using system Python. Make sure dependencies are installed." >&2
+    PYTHON_EXEC="python3"
+fi
+
+# Run the server
+exec "$PYTHON_EXEC" "$SCRIPT_DIR/gemini_server.py"