/standup

Generate standup notes from recent git activity

## Context

- Current git user: !`git config user.name`
- Current branch: !`git branch --show-current`
- Today: !`date +%A`
- Recent commits (24h): !`git log --author="$(git config user.name)" --since="24 hours ago" --format="%h %s" --all 2>/dev/null | head -10`

**If `$ARGUMENTS` is empty or not provided:**

Generate a standup for the default timeframe (24 hours, or 72 hours on Mondays).

**Usage:** `/standup [timeframe]`

**Examples:**

- `/standup` - Last 24 hours (72h on Mondays)
- `/standup 48h` - Last 48 hours
- `/standup 3d` - Last 3 days
- `/standup "since monday"` - Since Monday

*...