Optimize inefficient code patterns and eliminate redundancies

[Copilot]

Identified and removed performance bottlenecks and code inefficiencies across cryptographic operations, QR code generation, and test suite.

Performance Optimizations

• Direct JSON serialization: Use model_dump_json() instead of json.dumps(model_dump()) in QR code generation
• Explicit format specification: Add format="PNG" to img.save() to bypass format inference
• Remove redundant encoding parameters: Strip encoding="utf-8" from all .encode()/.decode() calls (UTF-8 is default)

# Before
data = json.dumps(encrypted_data.model_dump())
img.save(img_io)
key.encode(encoding="utf-8")

# After  
data = encrypted_data.model_dump_json()
img.save(img_io, format="PNG")
key.encode()

Code Quality

• Fix TemplateResponse deprecation: Update to TemplateResponse(request, name) signature
• Deduplicate test fixtures: Extract shared sample_encrypted_data to conftest.py, eliminating ~40 lines of duplication
• Prevent fixture mutation: Use model_copy(update={...}) instead of direct modification

Testing

• Add performance regression tests for encrypt/decrypt/QR generation operations
• Validate operations complete within expected timeframes

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• astral.sh
  • Triggering command: /usr/bin/curl curl -LsSf REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Identify and suggest improvements to slow or inefficient code

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.