Fix nutrition service error handling for unsupported pet types

[github-actions]

Summary

Fixes the nutrition service to handle unsupported pet types gracefully instead of returning 404 errors.

Changes Made

1. Graceful Fallback Implementation

• Modified /nutrition/:pet_type endpoint to return generic nutrition advice instead of 404 for unknown pet types
• Returns HTTP 200 with helpful veterinary guidance for unsupported pets
• Maintains API consistency while providing useful fallback content

2. Expanded Database Seed Data

• Added missing pet types: turtle, rabbit, fish, guinea pig
• Covers all pet types being queried by AI agents
• Prevents 404 errors for common pet types

Root Cause Analysis

The investigation revealed:

• 112 consecutive 404 errors on /nutrition/:pet_type endpoint (100% failure rate)
• Database only seeded 6 pet types but agents queried unsupported types like turtle, rabbit
• Complete service breakdown with zero successful requests

Impact

• ✅ Eliminates 100% failure rate for nutrition queries
• ✅ Provides helpful fallback advice for any pet type
• ✅ Maintains backward compatibility
• ✅ Improves user experience with actionable guidance

Testing

The changes ensure:

1. Known pet types return specific nutrition data
2. Unknown pet types receive generic veterinary advice
3. No more 404 errors for nutrition queries
4. Service remains functional for all pet type requests

Fixes the critical service breakdown identified in the Application Signals investigation.