Enable manual triggering for maintenance-fast.yml workflow

Add workflow_dispatch trigger to maintenance-fast.yml on main branch
to enable manual triggering with commit SHA input. GitHub only shows
manual trigger options for workflows that exist on the default branch,
so adding this trigger allows the maintenance-fast workflow to be
manually triggered from the GitHub UI.

The actual workflow implementation with commit checkout logic already
exists on the 1.0.x branch and will be used when manually triggered.

Signed-off-by: [email protected]

Author: markpollack

.github/workflows/maintenance-fast.yml

@@ -4,10 +4,16 @@ run-name: ${{ github.event.inputs.commit_sha && format('Manual Test - {0}', gith
 on:
   push:
     branches: ['*.*.x']
+  workflow_dispatch:
+    inputs:
+      commit_sha:
+        description: 'Specific commit SHA to test (optional - defaults to latest)'
+        required: false
+        type: string
 
 jobs:
   fast-impacted:
-    if: contains(github.event.head_commit.message, '(cherry picked from commit')
+    if: ${{ contains(github.event.head_commit.message, '(cherry picked from commit') || github.event_name == 'workflow_dispatch' }}
     runs-on: ubuntu-latest
     permissions:
       contents: read