Review feedback: the original guard substring-searched the whole file
after the first "csp" token, which (a) false-passes if any unrelated
JSON value elsewhere in the config happens to contain a localhost URL
and (b) false-fails if the CSP is ever re-serialised with escaped
forward slashes.
Switches to serde_json + a /app/security/csp pointer lookup, then
splits the CSP on ';', finds the connect-src directive, tokenises its
allow-list on whitespace, and requires an exact match for both
http://127.0.0.1:* and ws://127.0.0.1:*. The error now also includes
the current connect-src value so a developer who breaks it can see
exactly what needs restoring.