docs: document missing create-pull-request configuration options (#495)

Add missing config options to the create-pull-request section in
docs/safe-outputs.md. The following fields existed in CreatePrConfig
but were not documented:

- title-prefix: prefix prepended to all PR titles
- if-no-changes: behavior when patch is empty (warn/error/ignore)
- max-files: maximum files in a single PR (default: 100)
- protected-files: file protection policy (blocked/allowed)
- excluded-files: glob patterns for files to exclude from patch
- allowed-labels: allowlist of labels the agent may apply
- fallback-record-branch: record branch info on PR creation failure

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: jamesadevine <4742697+jamesadevine@users.noreply.github.com>

Author: 4 people

docs/safe-outputs.md

@@ -610,4 +610,3 @@ safe-outputs:
 Note: `wiki-name` is required. If it is not set, execution fails with an explicit error message.
 
 **Code wikis vs project wikis:** The executor automatically detects code wikis (type 1) and resolves the published branch from the wiki metadata. You only need to set `branch` explicitly to override the auto-detected value (e.g. targeting a non-default branch). Project wikis (type 0) need no branch configuration.
-