perf(shift-type): stop and clean up last_sync_of_checkin versions

[sagarvora]

Biometric checkin sync PUTs last_sync_of_checkin to /api/resource/Shift Type/<name> on every run — one Version record per sync, forever.

Stop creating them

New before_validate hook on Shift Type sets doc.flags.ignore_version when a resource PUT updates only that field.

• Bails out first on has_value_changed(last_sync_of_checkin), so the request is only inspected when the timestamp actually moved.
• Reads the payload via frappe.api.v1.get_request_form_data — the sync sends a raw JSON body with no Content-Type, so make_form_dict leaves form_dict empty and only request.get_data() recovers it. Also covers form-encoded data=<json> and query params.
• Gated to PUT on /api/resource/, /api/v1/resource/, /api/v2/document/. Desk saves, background jobs and /api/method/* are untouched.
• Strict single-key match — a PUT touching last_sync_of_checkin plus any other field versions normally.

Clean up the ones already there

csf_tz/patches/delete_shift_type_checkin_sync_versions.py, deliberately not in patches.txt — deleting history is a judgement call. Run via bench execute; estimate first, it only reads.

• Keyset-paginated on name over the indexed ref_doctype slice, deleted in small autocommitted batches. Resumable, and work is proportional to the Shift Type rows, not the table.
• Matching is done in Python, not SQL: Version.data's key-set depends on the frappe version that wrote the row (v11 emits four keys, v15 six, bare {"changed": …} also occurs), so it requires changed to hold only our field and no other key to carry a value. An unrecognised key with content means the row is kept.
• reclaim_space rebuilds the table afterwards to return space to the filesystem — optional, and wants a quiet window.

Measured 7k–13k rows/s deleting locally, so under two hours for 35M rows — one bench, not a promise.

Verification

Hook: fires for the sync's exact shape (raw body, no content-type) on all three resource paths; stays off for unchanged values, extra fields, other-fields-only, empty/absent body, POST, GET, /api/method/frappe.client.save, desk/background saves, and malformed payloads.

Patch: deletes the v15/v11/changed-only/null-previous shapes; keeps two-field diffs, row_changed/added/removed/data_import/updater_reference, unknown-key-with-content, insert markers, and malformed input. End-to-end Version counts and idempotent re-runs confirmed, plus batch boundaries across multi-batch walks.