Authorize non-force commit and push in PR Watch prompts

[SDSLeon]

Type: Feature

• Grant PR Watch tasks explicit user authorization to commit and push the exact non-force fixes needed on the PR head branch.
• Instruct watch agents not to ask for confirmation, refuse the push, or stop after a local-only commit.
• Keep force-push, merge, and unrelated changes out of scope.
• Cover the new prompt wording in PrWatchService tests.