fix: make daily penalty selectable and finalize payment on confirm

[Takeru-Habu]

What

• Change contract flow to PickApps -> CreateContract -> Payment -> ConfirmContract -> Dashboard
• Add selectable daily penalty (500-2000, step 100) and compute deposit as penalty * 7
• Execute Stripe payment and contract creation only on final confirmation
• Update create-contract Edge Function to accept/validate/persist penaltyPerDay
• Merge latest develop documentation updates and align design doc with current flow

Why

• Users need to choose their daily penalty amount instead of fixed 500
• Payment should be finalized only when the user confirms contract details
• Keep branch up to date with latest docs structure merged into develop

Check Lists

[x] Worked well on local environment
[x] Tests passed

ScreenShot (if you need)

Related Issues

Closes #47