feat(lab2): Threagile threat model + secure variant

[witch2256]

Goal

Complete Lab 2 — Threat Modeling: STRIDE on Juice Shop with Threagile

Changes

• Added submissions/lab2.md with baseline risk table, top-5 risks, STRIDE mapping, and trust boundary observation
• Added labs/lab2/threagile-model-secure.yaml — hardened variant (HTTPS, encrypted DB, prepared statements, TLS for webhook)

Testing

• Threagile v0.9.1 run against baseline model → output/risks.json generated
• Threagile v0.9.1 run against secure variant → output-secure/risks.json generated
• jq diff confirms risk reduction (3 risks removed)

Artifacts & Screenshots

• submissions/lab2.md (full analysis + tables)
• labs/lab2/threagile-model-secure.yaml

Checklist

• Title is clear
• No secrets committed
• Submission file exists

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• Task 1 — Baseline risk table + top-5 with STRIDE mapping
• Task 2 — Secure variant + risk diff table
• Bonus — Auth-flow model + 3 auth-specific risks