Stop scanning the request body for CRLF injection

A 403 "egress DLP: URL-encoded CRLF (%0d%0a)" was firing on legitimate
requests (e.g. the Claude Code login flow) and bypassing the on-match
policy entirely, because CRLF blocks carry no matched value and were
routed straight to a hard 403.

Root cause: CRLF injection is only an attack in the request line and
headers. An HTTP body is delimited by Content-Length, so CRLF bytes in
the body cannot split the request — but the scan flattened the body into
the same blob it checked, so form-encoded / multi-line body content
(which legitimately contains %0d%0a) tripped it.

Fix:
- scan_outbound takes a crlf_text param; the addon scans CRLF only over
  the body-excluded request line + headers. crlf_text=None keeps the
  old full-blob behavior for host-side callers/tests; the websocket path
  passes "" since a data frame is not a request line.
- The redact policy now also scrubs CRLF (new strip_crlf helper) from the
  path and headers, so redact is a complete escape hatch and structural
  CRLF in the URL/headers can be forwarded when a route opts into it.

Tests: strip_crlf unit tests; scan_outbound crlf_text body-exclusion and
backward-compat tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HnvBjPZC5V7qeQpFbQdDmS

tests/unit/test_dlp_detectors.py

@@ -487,5 +487,21 @@ class TestMatchedAndSafeTokens(unittest.TestCase):
         self.assertEqual("", result.matched)
 
 
+class TestStripCrlf(unittest.TestCase):
+    def test_removes_url_encoded_crlf(self):
+        from bot_bottle.dlp_detectors import strip_crlf
+        out = strip_crlf("next=%0d%0aX-Injected: evil")
+        self.assertNotRegex(out, r"%0[dD]%0[aA]")
+
+    def test_removes_literal_header_injection(self):
+        from bot_bottle.dlp_detectors import strip_crlf
+        out = strip_crlf("value\r\nX-Injected: evil")
+        self.assertIsNone(scan_crlf_injection(out))
+
+    def test_leaves_clean_text_unchanged(self):
+        from bot_bottle.dlp_detectors import strip_crlf
+        self.assertEqual("/api/v1/data?q=hello", strip_crlf("/api/v1/data?q=hello"))
+
+
 if __name__ == "__main__":
     unittest.main()