refactor: remove dead code, unused exports and redundant dependencies

- drop dotenv (Node 24 process.loadEnvFile) and dompurify (only used by dead code)
- delete unused ui components/hooks (card, progress, checkbox, use-confirm, use-prompt)
- delete dead sanitizeHtml/sanitizeCss, url-security helpers, patch-resume tool,
  schema/page, createResumePatches, patch-proposal preview builder, fonts fallback helpers
- inline single-caller wrappers (flags service, auth getSession, pdf renderer passthrough)
- deduplicate template color helpers into shared/color-helpers
- unexport 50+ internal-only symbols, remove dead export-map entries
- replace hand-rolled unique()/useIsMobile with Set spread and usehooks-ts

packages/pdf/src/section-title.ts

@@ -1,6 +1,6 @@
 import type { ResumeData, SectionType } from "@reactive-resume/schema/resume/data";
 
-export type SectionTitleResolverInput = {
+type SectionTitleResolverInput = {
 	sectionId: string;
 	locale: string;
 	sectionKind: "summary" | "builtin" | "custom";