feat: add draft_pr option to project config

[maxbeizer]

Summary

Add a draft_pr boolean option to ProjectConfig so all PRs opened by Nightshift for a given project are created as GitHub draft PRs.

This keeps CODEOWNERS out of the loop until the user has reviewed the AI-generated changes and manually converts the PR to ready-for-review.

Config usage

projects:
  - path: ~/code/myproject
    draft_pr: true   # all PRs opened for this project will be drafts

Also adds a --draft flag to nightshift task run for per-run control:

nightshift task run lint-fix --provider claude --draft

Changes

• internal/config/config.go — Added DraftPR bool field to ProjectConfig and ProjectByPath() helper
• internal/orchestrator/orchestrator.go — Added DraftPR to RunMetadata, modified buildImplementPrompt() to instruct agents to use gh pr create --draft when enabled
• cmd/nightshift/commands/run.go — Wire draft_pr from project config into RunMetadata
• cmd/nightshift/commands/task.go — Add --draft CLI flag, fall back to project config
• Tests — Added tests for config lookup, draft/non-draft prompt generation

Testing

All existing tests pass. New tests cover:

• TestProjectByPath — config lookup by path
• TestBuildImplementPrompt_DraftPR — draft instruction in prompt
• TestBuildImplementPrompt_NoDraftPR — no draft instruction when disabled
• TestBuildImplementPrompt_DraftPR_NoMetadata — graceful handling with no metadata

Closes #23

[maxbeizer]

I kind of wonder whether draft should be the default and we invert this 🤔

[maxbeizer]

@marcus i think this is a really cool project 💖 . So I thought I'd fire up a PR (with copilot). Hope you like it.

As noted in #53 (comment) I actually wonder if instead of this, the default behavior should be draft and you have to explicitly enable "ready" PRs. Curious what you think

[marcus]

Hey @maxbeizer! Starling here (AI assistant on the project). 👋

First — welcome, and thank you for this burst of work. Four coordinated PRs to flesh out Copilot support end-to-end is a tremendous first contribution:

• feat: wire Copilot provider Execute() to agent and add PRU multipliers #54 — Copilot provider Execute() wired to the agent + PRU multiplier map
• feat: add PRU-aware budget config with Copilot plan presets #55 — PRU-aware budget config with plan presets
• docs: add COPILOT_INTEGRATION.md #56 — COPILOT_INTEGRATION.md filling the missing doc gap
• feat: add draft_pr option to project config #53 — draft_pr project config + --draft CLI flag

Each one is cleanly scoped and ships with tests. Really appreciate the care here.

On your question about draft-as-default vs. opt-in: that's a meaningful design decision with real tradeoffs. Draft-by-default is the safer posture for AI-generated PRs (keeps CODEOWNERS quiet until the human reviews), but it's a behavior change for existing users and adds friction for solo projects where draft is just noise. No obvious right answer — surfacing to Marcus to make the call.

I'll do a review pass through the series and be back with notes. ✦