Rehome 11 LiveStream 053.1 files from LiveStream_052, then migrate the 22 remaining LiveStream_053 files #23

• Series: Livestream
• Files: 33
• Estimated time: ~90 minutes
• Labels: good-first-issue, i16-translations

Eleven translation files named "ActInf Livestream 053.1 ~ Snakes and Ladders…" sit in the LiveStream_052 item (misfiled — they belong to LiveStream_053 part iHgxmn0ockg); LiveStream_053 itself also still holds 22 of its own unmigrated files (11 × #053.0 → c7ybFyP9KrI, 11 × #053.1 → iHgxmn0ockg). Do the rehome first, then the in-item migrations.

Scope (from the triage doc, Part A):

• Item Livestream/LiveStream_052 → rehome into Livestream/LiveStream_053
  • 11 files, stem ActInf Livestream 053.1 ~ 'Snakes and Ladders in Paleoanthropology' & 'To copy or not to copy' → target translations/iHgxmn0ockg.<bcp47>.srt
• Item Livestream/LiveStream_053
  • 11 files, stem ActInf Livestream 053 0 'Snakes and Ladders in Paleoanthropology' & 'To copy or not to copy' → target translations/c7ybFyP9KrI.<bcp47>.srt
  • 11 files, stem ActInf Livestream 053.1 ~ 'Snakes and Ladders in Paleoanthropology' & 'To copy or not to copy' → target translations/iHgxmn0ockg.<bcp47>.srt

Read first: docs/volunteer-transcript-tasks.md —
sections "The 30-minute task (per file)" and "Exact command pattern".

Steps, per file:

1. Verify the guessed video_id in the item's metadata.json + a YouTube spot-check of the part.
2. Confirm the language by opening the .srt (normalize legacy codes per the migration map).
3. Move with the two-step git mv into translations/<video_id>.<bcp47>.srt.
4. Append the original repo-relative path to the destination item's metadata.json previous_paths.
5. One path-scoped commit per item: translations(<series>): migrate <N> legacy files (I16 triage).

Acceptance criteria:

• every listed file moved (or deleted, if byte-identical to an already-migrated target) with previous_paths recorded
• no listed file remains in the item's Translations/ folder; empty Translations/ and translations_tmp/ removed
• spot-checked target files open as valid subtitles and match the verified part/language