feat(codex-local): add fast mode support

ui/src/components/agent-config-defaults.ts

@@ -10,6 +10,7 @@ export const defaultCreateValues: CreateConfigValues = {
   chrome: false,
   dangerouslySkipPermissions: true,
   search: false,
+  fastMode: false,
   dangerouslyBypassSandbox: false,
   command: "",
   args: "",

ui/src/components/agent-config-primitives.tsx

@@ -34,6 +34,7 @@ export const help: Record<string, string> = {
   dangerouslySkipPermissions: "Run unattended by auto-approving adapter permission prompts when supported.",
   dangerouslyBypassSandbox: "Run Codex without sandbox restrictions. Required for filesystem/network access.",
   search: "Enable Codex web search capability during runs.",
+  fastMode: "Enable Codex Fast mode. This burns credits/tokens much faster and is currently supported on GPT-5.4 only.",
   workspaceStrategy: "How Paperclip should realize an execution workspace for this agent. Keep project_primary for normal cwd execution, or use git_worktree for issue-scoped isolated checkouts.",
   workspaceBaseRef: "Base git ref used when creating a worktree branch. Leave blank to use the resolved workspace ref or HEAD.",
   workspaceBranchTemplate: "Template for naming derived branches. Supports {{issue.identifier}}, {{issue.title}}, {{agent.name}}, {{project.id}}, {{workspace.repoRef}}, and {{slug}}.",