fix: replace all any request types with typed AuthRequest interface

[karanjadavi]

• Add shared JwtUser and AuthRequest interfaces in src/common/types/auth-request.interface.ts
• Update JwtStrategy.validate() to return typed JwtUser with sub field
• Replace @request() req: any across users, admin, milestones, campaigns controllers
• Replace @Req() req: Request & { user: any } in donations, notifications, api-keys controllers
• Add AuthenticatedSocket interface in notifications.gateway.ts to remove (client as any) casts
• Replace as any casts in users.service.ts with Prisma.InputJsonValue and typed assertions
• Replace as any casts in campaigns.service.ts with Number(), Prisma.EnumCampaignStatusFilter, and type guard
• Fix soroban.service.ts XDR response casts and scValResult double-cast via unknown
• Fix email.service.ts (info as any).message with narrowed type
• Enable @typescript-eslint/no-explicit-any: error in eslint.config.mjs to prevent regressions

Closes #17

[Alqku]

@karanjadavi please fix the CI.

[Alqku]

Direction is good — typed AuthRequest is a real improvement. Heads up: CI is red on lint/build, so flipping @typescript-eslint/no-explicit-any to error surfaces a few leftover anys in src/auth, src/stellar, etc. that this PR didn\u2019t catch. Can you tighten those up and re-run? Happy to merge once CI is green.