[yh12-10]

Image processing could lose reproducibility across concurrent jobs, completed results could become inaccessible, and the workflow could discard authenticated deep links. This change fixes those paths and rebuilds the interface as a consistent camera and film studio.

• Redesign the home, authentication, upload, batch, library, comparison, and admin views with responsive layouts, keyboard controls, local fonts, and real pipeline samples.
• Isolate session caches, handle loading and failure states, preserve batch links, and provide reliable JPEG and ZIP downloads.
• Validate and normalize image uploads, bound processing work, stage batches atomically, refresh stored URLs, and retain compatibility with historical output keys.
• Make processing deterministic per image and intensity. Preserve legacy video records in a durable archive during migration, including interrupted upgrade retries.
• Document upgrade behavior and verified security boundaries.

Validation: TypeScript, Prettier, production build, and all 71 tests pass. Migration tests ran against MySQL 8 with strict SQL mode and interruption at every migration statement. Browser checks covered desktop and 320/390-pixel mobile layouts, signup, upload, processing, refresh, batch processing, comparison, and sign-out. HTTP checks verified three JPEGs in the ZIP, JPEG attachment downloads, and ownership/authentication boundaries. Test runs leave .env unchanged.

Upgrade: stop the previous application and apply migrations before starting this version; see UPGRADING.md. Records deleted by an older deployment require that deployment's backup. S3 behavior is covered by contract tests; no live bucket was used.