[translate] Sync cleanup after action-translation v0.12.2

[mmcky]

Translation sync cleanup after action-translation v0.12.2

action-translation v0.12.2 fixes two bugs that affected the translation PRs generated for this repo:

1. Heading-map position fallback — when a new section was added to source but the translation PR hadn't been merged yet, the position fallback grabbed the wrong target section, producing incorrect heading-map values.
2. Resync SHA — \translate-resync was diffing HEAD vs HEAD instead of the PR's actual merge commit, so it couldn't detect the PR's changes.

Current state

Target repo	PR	Title	Issue
.zh-cn	#3	Add Type Hints section	Generated with v0.12.1 (has heading-map bug)
.zh-cn	#4	Fix broken raw GitHub URLs	Superset — includes Type Hints changes too
.fa	#70	Add Type Hints section	Generated with v0.12.1 (has heading-map bug)
.fa	#71	Fix broken raw GitHub URLs	Superset — includes Type Hints changes too

Recommended sequence

1. Update both workflows to @v0.12.2 (PR forthcoming)
2. Merge zh-cn missing content directive  #3 and fa [CI] Update once sphinx-exercise merges PR #16 #70 (Type Hints — the heading-map bug only affects the map metadata, the actual translation content is correct)
3. Close zh-cn Fixes Needed for sphinxcontrib-tomyst #4 and fa [gh-pages] Support for home needed #71 (stale supersets)
4. Run \translate-resync on source PR Fix broken raw GitHub URLs for CSV data files #491 to generate clean URL-fix-only translation PRs with v0.12.2

This will produce translation PRs that each contain only the changes from their respective source PRs, with correct heading-map values.