Centralize Routing

Prompt file imported from quasydwekat2/chripy (.github/prompts/centralize-routing.prompt.md). Copyright stays with the author.

Refactor the current Express app so routing is centralized in a dedicated route module.

Use the existing codebase context and preserve behavior:

• Identify route registrations currently defined inline in src/server.ts.
• Create or update a route module under src/ to hold the route registrations in one place.
• Move route setup into a reusable function such as registerRoutes(app) or equivalent.
• Update src/server.ts to import and call the route module instead of defining the routes inline.
• Keep middleware order and request behavior unchanged, including logging, metrics, static file serving, health, validation, admin metrics, reset, and 404 handling.
• Preserve current handler implementations unless a small adjustment is required to support the routing extraction.
• Keep the change minimal and consistent with the project style.

If the codebase already has a preferred routing pattern, follow that pattern instead of introducing a new one. After editing, verify the app still compiles and that the route wiring is correct.