feat: Add plugin configuration editing with template variable parsing

## Backend Changes:
- Enhanced PluginTemplate.save() to auto-parse template variables from plugin code
- Updated PluginInstallationSerializer to expose template metadata (description, category, version, author, logo, template_variables)
- Fixed template variable parser to handle nested {{ }} braces in default values
- Added brace-counting algorithm to properly extract variables with insertion codes
- Fixed explicit type parameter detection (textarea, text, email, etc.)
- Made scheduled_task optional on PluginInstallation model
- Added EventPlugin through model for event-plugin relationships
- Added Event.execute_plugins() method for plugin automation

## Frontend Changes:
- Created Tasks.tsx page for managing scheduled tasks
- Enhanced MyPlugins page with clickable plugin cards
- Added edit configuration modal with dynamic form generation
- Implemented escape sequence handling (convert \n, \', etc. for display)
- Added plugin logos to My Plugins page
- Updated type definitions for PluginInstallation interface
- Added insertion code documentation to Plugin Docs

## Plugin System:
- All platform plugins now have editable email templates with textarea support
- Template variables properly parsed with full default values
- Insertion codes ({{CUSTOMER_NAME}}, {{BUSINESS_NAME}}, etc.) documented
- Plugin logos displayed in marketplace and My Plugins

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

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

frontend/public/plugin-logos/test_google_genai.py

@@ -0,0 +1,41 @@
+from google import genai
+from google.genai import types
+from PIL import Image
+from io import BytesIO
+import os
+
+# Initialize the Client
+client = genai.Client(api_key="AIzaSyB-nR0nkeftKrd42NrNIDcFCj3yFP8JLtw")
+
+# Define the prompt
+prompt = "A simple modern app icon with a blue background and white envelope symbol, square format, flat design"
+
+print(f"Generating image for: '{prompt}'...")
+
+# Call the API
+try:
+    response = client.models.generate_images(
+        model='gemini-2.5-flash-image',
+        prompt=prompt,
+        config=types.GenerateImagesConfig(
+            number_of_images=1,
+            aspect_ratio="1:1",
+            safety_filter_level="BLOCK_LOW_AND_ABOVE",
+            person_generation="ALLOW_ADULT"
+        )
+    )
+
+    # Handle the response
+    for i, generated_image in enumerate(response.generated_images):
+        # Convert raw bytes to an image
+        image = Image.open(BytesIO(generated_image.image.image_bytes))
+
+        # Save to disk
+        filename = f"test_generated_image_{i}.png"
+        image.save(filename)
+        print(f"Success! Saved {filename}")
+
+except Exception as e:
+    print(f"Error occurred: {type(e).__name__}: {e}")
+    import traceback
+    traceback.print_exc()