feat: add TimedAward module with auto-unpause for paused streams

[lishmanTech]

• Introduced TimedAwardContract to manage awards with streaming payouts
• Supports immediate initial payout and remainder streaming over a duration
• Added pause_award() to allow DAO to pause a stream
• Automatic unpause after 14 days if DAO does not act, preventing grantees from being stuck
• withdraw() calculates accrued funds based on pause state and automatically resumes streams when pause expires
• Fully modular implementation in new file timed_awards.rs

closes #84