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/generate_with_2_0_flash.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+from google import genai
+from google.genai import types
+from PIL import Image
+from io import BytesIO
+
+# Setup Client
+client = genai.Client(api_key="AIzaSyB-nR0nkeftKrd42NrNIDcFCj3yFP8JLtw")
+
+# Test with a simple prompt
+prompt = "Create a simple modern app icon with a blue background and white envelope symbol, square format, flat design, minimalist"
+
+print(f"Testing gemini-2.0-flash-exp...")
+print(f"Prompt: '{prompt}'...")
+
+try:
+    response = client.models.generate_content(
+        model='gemini-2.0-flash-exp',
+        contents=prompt,
+        config=types.GenerateContentConfig(
+            response_modalities=["IMAGE"]
+        )
+    )
+
+    # Save the Image
+    if response.candidates[0].content.parts:
+        for part in response.candidates[0].content.parts:
+            if part.inline_data:
+                image_data = part.inline_data.data
+                image = Image.open(BytesIO(image_data))
+                image.save("test_2_0_flash.png")
+                print("✓ Success! Saved test_2_0_flash.png")
+            else:
+                print(f"✗ Model returned text: {part.text[:100]}")
+    else:
+        print("✗ No content parts in response")
+
+except Exception as e:
+    print(f"✗ Error: {type(e).__name__}: {str(e)[:300]}")