[portfolio] remove tracked environment and add project controls

[RidhanPar]

What changed

• remove 14,044 accidentally tracked virtual-environment files and tracked Python caches
• replace the hard-coded Flask secret with deployment configuration and add a request-size limit
• add validation for comparisons with no matching student IDs
• add tests, CI, Render secret generation, and evidence/security documentation

Validation

• 7 tests passed
• compileall passed
• tracked-file count reduced from 14,082 to 33
• git diff --check passed