Add cooldown to dependabot and expand .gitignore

[potiuk]

Summary

• Add cooldown configuration to dependabot
• Expand .gitignore with standard Python project patterns (bytecode, venvs, coverage, IDE files, etc.)
• Remove .idea/ from tracking

Test plan

• Verify dependabot respects the new cooldown setting
• Confirm ignored files are no longer tracked

Generated-by: Claude Opus 4.6 (1M context)

[potiuk]

I will merge it quickly @raboof -> because this will prevent our dependabot to suggest upgrades immediately. But we can discuss details of this and update it later to other values or discuss other strategies - for now it's absolutely no harm to delay those - nobody was merging those PRs for weeks anyway.

[raboof]

we can discuss details of this and update it later to other values or discuss other strategies

Yes, let's discuss in #607

for now it's absolutely no harm to delay those - nobody was merging those PRs for weeks anyway.

While it is definitely true there were dependabot PRs that were not merged for weeks, there were also PRs that were getting merged quickly. I think the ideal situation here would be that people who actually use actions review their updates, as they have a stake in it and are best-positioned to judge whether the changes look healthy.