Unify PR creation codepaths for conflict/non-conflict syncs.

[vorporeal]

Description

Unifies the conflict and non-conflict codepaths in both _sync_private_to_public and _sync_public_to_private.

Previously, a cherry-pick conflict caused the code to branch into a completely separate _handle_cherry_pick_conflict function that duplicated much of the standard flow (description building, trailer appending, push, PR creation). This made it easy for the two paths to drift — most recently, conflict PRs were getting [CONFLICT] prepended to their titles and losing their original PR descriptions.

Now both functions follow a single linear flow with is_conflict conditionals at the points where behavior differs:

1. Cherry-pick → set is_conflict
2. Commit handling (raw conflict commit + resolution agent vs. amend)
3. Build PR description (shared, identical logic)
4. Append trailers (origin always; conflict trailer only if conflict)
5. Push + create PR
6. Post-creation conflict steps if needed (label, reviewer, comment, slack)

Other changes:

• Conflict PRs no longer get [CONFLICT] prepended to their title.
• Conflict PRs now preserve the original description (source PR body or agent-generated) instead of replacing it with a generic conflict message.
• A comment is posted on conflict PRs noting the reviewer assignment, rather than baking that info into the PR body.
• Added GhOps.add_pr_comment() method.

Testing

All 251 existing tests pass. Verified via manual inspection of a conflict sync PR (warpdotdev/warp-internal#24195).

Co-Authored-By: Oz oz-agent@warp.dev

[vorporeal]

• Unify PR creation codepaths for conflict/non-conflict syncs. #20 👈 (View in Graphite)
• main

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