Show full Codex fingerprint identities and patch Go security

[HTExplicit]

The Codex fingerprint page hid most of the account's saved device identity and required a separate click to inspect it. It now loads and shows the complete device identity, selected UA device fields, current policy, and identifier handling rules automatically. Saved identities remain visible when simulation is disabled; protocol fallback and request-dependent values are explicitly distinguished.

The existing account endpoint adds three read-only fields while PUT remains mode-only. Detail reads are bounded to three, obsolete page/policy/mode responses are ignored, and reading or refreshing preserves unsaved mode drafts. Identity generation, forwarding policy, database schema, and saved production settings remain unchanged.

The required security scan identified reachable vulnerabilities in the existing Go standard library and x/net versions. Build and CI now use Go 1.27.2; x/net is upgraded to v0.60.0 with its minimum required module versions. All three Dockerfiles and the existing Go-version assertions use the same patched version.

Lint uses v2.14.0 to support the patched Go export data. The existing HTTP/2 bridge is retained to preserve the independently configured H2C idle timeout, transport registration and GOAWAY compatibility. Only SA1019 on the named compatibility symbols in five paths is exempted; all other diagnostics and security/type checks remain enabled. The compatibility edits are comments/formatting, with no runtime statement changes.

Validation:

• Targeted account-view, admin-handler, and WS proxy TLS-handshake tests passed with Go 1.27.2.
• HTTP/2 keepalive and stream-close isolation tests passed; all Go modules verified.
• Frontend: 10 existing targeted cases passed, plus the 2 subsequently added cases passed; unchanged results reused.
• Vue typecheck, focused ESLint, source/static checks, and git diff checks passed. Unchanged frontend validation is reused.
• Normal required checks, including golangci-lint, security scans and the candidate image, gate merge on the final head.
• No real model calls.