feat(egress): implement PRD 0053 — DLP addon with Gateway API matches

Replace path_allowlist with Gateway API HTTPRoute match vocabulary
(paths, methods, headers with AND/OR semantics) and add DLP scanning
to the egress proxy:

- Token pattern detection (AWS, GitHub, Anthropic, OpenAI, Stripe, JWT)
- Known secret detection (EGRESS_TOKEN_* with base64/URL/hex variants)
- Naive prompt injection detection (disclosure + credential, jailbreak)
- Per-route DLP configuration via manifest dlp block
- Inbound response scanning with block/warn severity

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Dockerfile.sidecars

@@ -63,6 +63,7 @@ COPY --from=gitleaks-src /usr/bin/gitleaks /usr/bin/gitleaks
 # Dockerfile.egress / Dockerfile.supervise layout.
 COPY bot_bottle/egress_addon_core.py /app/egress_addon_core.py
 COPY bot_bottle/egress_addon.py      /app/egress_addon.py
+COPY bot_bottle/dlp_detectors.py     /app/dlp_detectors.py
 COPY bot_bottle/yaml_subset.py       /app/yaml_subset.py
 COPY bot_bottle/supervise.py         /app/supervise.py
 COPY bot_bottle/supervise_server.py  /app/supervise_server.py