feat: bounty creation nostr

[lambdakilo]

Summary

sign a nostr event using ndk in the bounty creation ui. example of a succesful broadcasting can be seen here:

https://njump.me/nevent1qvzqqqr4vgpzqwqhn9g4wz8y0ddx43wr9rsaup4tu20xcue8m8vn9x252ttne4qeqy28wumn8ghj7un9d3shjtnyv9kh2uewd9hsz9nhwden5te0wfjkccte9ec8y6tdv9kzumn9wsqs6amnwvaz7tmwdaejumr0dsqzpasmt4z2kntna02h8n928pp4vxflyux5a9hqa7dk4t9m458n3fs9shem6z

Related issue

Resolves #13, resolves #8

Changes made

• create bounty.ts that handles the broadcasting to nostr via ndk, make integration tests and change /bounties/new svelte for the changes

Author checklist

bun run pr runs all the commands below in one go.

• Matches the spec
• bun run format - code has been formatted
• bun run lint - no prettier/eslint errors
• bun run check - no svelte-check/TypeScript errors
• bun run test - all tests pass
• bun run build - build succeeds
• I tested the relevant changes manually

Reviewer manual testing checklist

• check especially the bun run test on how it behaves on your computer. it uses playwright and probably chromium to mock the whole process
• you can optionally check if the new bounty is posted on nostr but remember to use your debug nsec

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[guildm4ster]

LGTM 👍 next step: display real events on the landing page

[lambdakilo]

good catches @guildm4ster lgtm