Remove invalid 'copilot' assignee from issue creation

[Copilot]

GitHub API returns 422 validation error when creating issues with assignees: ['copilot'] because 'copilot' is not a valid collaborator username.

Changes

• views/RepoDetail.tsx: Removed assignees field from issue creation payload
• README.md: Updated documentation to reflect auto-labeling only (no auto-assignment)

The jules label remains for AI agent tracking. Assignees can still be set manually through GitHub's UI when needed.

// Before
await createIssue(token, owner, repo, {
  title: newTitle,
  body: newBody,
  labels: ['jules'],
  assignees: ['copilot']  // ❌ Invalid
});

// After
await createIssue(token, owner, repo, {
  title: newTitle,
  body: newBody,
  labels: ['jules']  // ✅ Valid
});

Original prompt

---

This section details on the original issue you should resolve

<issue_title>fix</issue_title>
<issue_description>{
"message": "Validation Failed",
"errors": [
{
"value": [
"copilot"
],
"resource": "Issue",
"field": "assignees",
"code": "invalid"
}
],
"documentation_url": "https://docs.github.com/rest/issues/issues#create-an-issue",
"status": "422"
}
</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes fix #3

---

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[github-actions]

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Branch: copilot/fix-issue-validation-error
Commit: a6c40bd