feat(actions): add branch filters to run list (#37826)

## Summary

- Add a Branch filter dropdown to the repo Actions run list web UI
- Wire `?branch=` query param through the web handler, matching the
existing REST API filter behavior
- Source the Branch dropdown from the indexed `branch` table (filtering
out deleted branches) instead of scanning `action_run.ref`, addressing
review feedback about unindexed columns

The Event filter was dropped after review: a static list of supported
events was noisy as UX, and querying distinct values from
`action_run.trigger_event` is slow because the column is not indexed.
`FindRunOptions.TriggerEvent` is kept for the REST API.

Closes #25042

---------

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

templates/repo/actions/workflow_dispatch.tmpl

@@ -7,7 +7,7 @@
 </div>
 <div id="runWorkflowDispatchModal" class="ui tiny modal">
 	<div class="content">
-		<form id="runWorkflowDispatchForm" class="ui form ignore-dirty" action="{{$.Link}}/run?workflow={{$.CurWorkflow}}&actor={{$.CurActor}}&status={{.Status}}" method="post">
+		<form id="runWorkflowDispatchForm" class="ui form ignore-dirty" action="{{$.Link}}/run?workflow={{$.CurWorkflow}}&actor={{$.CurActor}}&status={{$.CurStatus}}&branch={{$.CurBranch}}" method="post">
 			<div class="ui inline field required tw-flex tw-items-center">
 				<span class="ui inline required field">
 					<label>{{ctx.Locale.Tr "actions.workflow.from_ref"}}:</label>