docs: rename PRD 0053 to PRD 0052

Renames docs/prds/0053-egress-dlp-addon.md to 0052-egress-dlp-addon.md
and updates all references in the documentation.

docs/prds/0052-egress-dlp-addon.md

@@ -1,4 +1,4 @@
-# PRD 0053: Egress DLP addon
+# PRD 0052: Egress DLP addon
 
 - **Status:** Active
 - **Author:** claude
@@ -397,7 +397,7 @@ afterward, preserving the existing credential-injection security model.
 4. **Naive prompt injection detector (Phase 2).**
    Add `NaiveInjectionDetector` to `dlp_detectors.py`. Wire
    `scan_inbound` into the new `response` hook in `egress_addon.py`.
-   Extend unit tests. Activate PRD 0053 (`Status: Draft → Active`) in
+   Extend unit tests. Activate PRD 0052 (`Status: Draft → Active`) in
    this commit.
 
 ## Open questions