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>

bot_bottle/manifest.py

@@ -18,7 +18,7 @@ Bottle schema (frontmatter):
     user:       { name: <str>, email: <str> }   # optional
     repos:      { <name>: <git-gate-entry>, ... }  # optional
   egress: { routes: [ <egress-route>, ... ] }
-    # route keys: host, path_allowlist, auth, role
+    # route keys: host, matches, auth, role, dlp
   supervise:    <bool>                          # optional
 
 Agent schema (frontmatter):