Add Slack/webhook notification for new findings

[raphgm]

Reserved for the SKILL.SCH open source community.\n\nRight now findings only surface via findings list or the dashboard — someone has to remember to check. A simple cloudcost policy run --notify <webhook-url> (or a config option) that POSTs a summary (new findings since last run, total $ impact) to a Slack incoming webhook or generic webhook URL would make this usable as a real scheduled job that proactively surfaces waste instead of waiting to be checked.

[PreciousNwafor]

Hello Sir,

I am interested in working on this issue. I noticed you marked it as a good first issue and that it currently has no assignee. Would it be okay for me to take this one?

I am also relatively new to contributing to the project, so I would appreciate any guidance on the expected implementation approach.

Thank you.