[BE] GET latest mission draft for current user

[Kaylahray]

Description

POST /missions/drafts exists; creators also need GET to resume the wizard/edit flow.

User Story

As a Founder,
I want to reload my saved draft,
so that the create/edit wizard can resume.

Requirements and Context

• Files: backend/src/missions/
• JWT; return latest draft or 404; tests

Suggested Implementation

// GET /missions/drafts/me

Acceptance Criteria

• Returns latest draft for caller
• 404 when none
• Auth required
• Test covered

Submission Guidelines

• Branch: feat/be-get-draft
• Depends on: Existing draft POST
• PR: feat(backend): get latest mission draft for creator

[TechBroAfrica]

Hi! I'm interested in working on this task. I'll take the time to understand the codebase and requirements before implementing a clean, maintainable solution. I'll thoroughly validate my changes, keep communication clear throughout the process, and respond promptly to any review feedback.

[3m1n3nc3]

Hi mytainer, I would love to work on this issue. I have experience building APIs and backend resources and believe I can deliver this in record time.

[grantfox-oss]

🦊 GrantFox — @3m1n3nc3 has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #269)
2. Your PR will be reviewed by the Quid-proquo maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@3m1n3nc3's PR #276 was approved and merged by @Kaylahray.

🏆 @3m1n3nc3: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (166 total points). Track your full progress on GrantFox.

👏 Great work, @3m1n3nc3! Keep contributing to Quid-proquo.