refactor BWS express app routes

[tmcollins4]

Description

Refactors BWS ExpressApp route registration by moving route groups out of src/lib/expressapp.ts and into focused modules under src/lib/expressapp/.

This keeps the existing route behavior intact while making expressapp.ts smaller and easier to maintain. This is the first PR in a planned series to organize the larger BWS expressapp.ts and server.ts files into smaller modules.

Changelog

• Move ExpressApp route registration into focused modules under src/lib/expressapp/.
• Add shared ExpressApp route context/helper setup for common route dependencies.
• Keep src/lib/expressapp.ts focused on app construction, middleware setup, limiter creation, and route registration orchestration.
• Preserve upstream wallet route updates, including /v1/wallets/exist and the /v1/wallets/all response handling fix.

Testing Notes

• Ran BWS lint and production build.
• Ran the BWS ExpressApp tests.
• Ran BWC lint and test suite.
• Also ran the full BWS test suite.

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Checklist

• I have read CONTRIBUTING.md and verified that this PR follows the guidelines and requirements outlined in it.