Re-enable draft_admin_integrity only after deploying real ADMINSERVICE_*_DRAFTS cascade constraints #2993

Context

#2909 enabled CAP 10.2 cds.fiori.draft_admin_integrity: true to get optimized (DB-level cascade) draft deletion. But the required ON DELETE CASCADE .hdbconstraint files were never generated or deployed, so the flag ran with no supporting DB structure and corrupted drafts — every mission draft activate/discard orphaned child draft rows, making missions un-editable in PROD (2026-11-02 outage).

#2992 (merged to DEV) disabled the flag for all profiles and fixed the preflight check (which had been validating non-existent com_sap_developers_ims_*_drafts table names instead of the real ADMINSERVICE_*_DRAFTS). That stops the bleeding but does not deliver the #2909 optimization.

What this issue tracks

Re-enabling draft_admin_integrity correctly, if we still want the cascade benefit. Required before the flag can be turned back on:

1. Generate the real cascade constraints. Confirm how cds build emits the ON DELETE CASCADE FK on each ADMINSERVICE_<ENTITY>_DRAFTS.DRAFTADMINISTRATIVEDATA_DRAFTUUID → DRAFT_DRAFTADMINISTRATIVEDATA(DRAFTUUID). If the build does not emit them for HANA, author the .hdbconstraint artifacts explicitly (NOT VALIDATED first, per the deploy-before-serve ordering in CLAUDE.md gotcha "Optimized draft deletion").
2. Deploy constraints to HANA BEFORE flipping the flag (DEV → prod), on all *_DRAFTS tables that carry the FK column.
3. Verify via the now-fixed preflight — srv/lib/draft-integrity-preflight.js discovers draft tables from SYS.TABLE_COLUMNS and reports found/total. It must log verified (N/N) (not a WARN) on the target env.
4. Then set cds.fiori.draft_admin_integrity: true again (package.json) and redeploy.
5. Add a smoke/integration check that draftEdit→discard on a Mission leaves zero orphaned child draft rows.

Guardrails

• Do NOT re-enable the flag until steps 1–3 are green on the target environment.
• The runtime CDS_* env override does NOT work on the deployed build (verified during the outage) — the flag state is whatever is baked into package.json at build time.

Related: #2909 (introduced), #2968 (preflight), #2992 (disable + preflight fix).