ci(docs[paths-filter]) Fix python_files path for src layout

why: The filter used vcspull/** but sources live under src/vcspull/**
so Python file changes never triggered PUBLISH, meaning docs have
never been rebuilt on source changes since the src layout was adopted.
Also adds workflow_dispatch to allow manual doc rebuilds.
what:
- vcspull/** -> src/vcspull/** in python_files filter
- Add workflow_dispatch trigger

Author: tony

.github/workflows/docs.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - master
+  workflow_dispatch:
 
 permissions:
   contents: read
@@ -31,7 +32,7 @@ jobs:
               - 'docs/**'
               - 'examples/**'
             python_files:
-              - 'vcspull/**'
+              - 'src/vcspull/**'
               - pyproject.toml
               - uv.lock