feat: add SolFoundry bounty flow GIF

[ScryUser]

Summary

• Adds a loop-friendly animated GIF for the SolFoundry bounty flow under assets/animations/solfoundry-bounty-flow-831
• Shows the complete required sequence: create bounty -> fund -> submit -> AI review -> payout
• Reworked the layout so the progress row, active-step art, status badge, and footer text are separated into bounded regions without overlapping bars or cards
• Includes a README and manifest with dimensions, stored frame count, duration, file size, and flow metadata

Verification

• Validated GIF metadata: 960x540, 61 stored frames, loop enabled
• Confirmed file size is 2.28MB, under the 10MB requirement
• Ran git diff --check
• Visually reviewed a sampled contact sheet across the loop

Closes #831

Solana wallet: C2z3FWAacvSYVrrkfpk6nQyNhF4t3z7t9iXRW1xfZPy1