chore: close db-attribute removal (TML-2988) (#1062)

- **Intent:** Close the completed `@db.*` hard-cut project after PR
#1054 merged at `ca1f3a16b`; retain the mandatory final-retro learning
as F27.
- **Linear:** Refs:
[TML-2988](https://linear.app/prisma-company/issue/TML-2988) · [Remove
@db.* attributes from
PSL](https://linear.app/prisma-company/project/remove-db-attributes-from-psl-7f387115b0fc)
- **Scope:** Project DoD evidence: all four hard-cut slices are
complete; close-out material was classified as transient, while ADR 241
and F27 are durable; the external-reference scan found no references
outside the removed project tree.
- **Verification:** `git diff --check origin/main...HEAD` and tracked
close-out integrity only: the diff retains F27 while deleting the
classified transient artefacts.


<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit

* **Documentation**
* Made a minor whitespace/formatting adjustment around the boundary
between two failure-mode sections (no content added or changed).
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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Signed-off-by: Serhii Tatarintsev <tatarintsev@prisma.io>

Author: SevInf