Add API versioning strategy ahead of breaking changes

[Mkalbani]

Description

The API surface has grown quickly (search, analytics, ranking, moderation) with no versioning in place, meaning any future breaking change (e.g. the pagination migration) risks breaking existing consumers with no transition path. Introduce explicit versioning before more breaking changes land.

Acceptance Criteria

• NestJS URI-based versioning (/v1/...) enabled at the application level
• All existing routes namespaced under /v1 with redirects or aliases from the old unversioned paths for a deprecation period
• A documented deprecation policy (e.g. minimum notice period) added to CONTRIBUTING.md or docs/
• Swagger/OpenAPI docs (if present) reflect the versioned paths
• CI includes a check that new breaking changes to /v1 routes are flagged in PR review (e.g. a checklist item or lint rule)

[Oluwasuyi-Oluwatimilehin-Daniel]

Hi Maintainer, reviewed the issue in detail. Full stack background with solid experience relevant to this task. No blockers on my end — I'm ready to submit a PR shortly. Please assign.

[Truphile]

Hi team! I'd love to take this on.
​I'll handle the core implementation, keep the state/data layers in sync, handle edge cases cleanly, and ship it with solid tests.
​Ready for assignment to drop a PR!

[mijinummi]

Hello maintainers I'm a full stack developer experience in building scalable systems I can handle this perfectly

[grantfox-oss]

🦊 GrantFox — @mijinummi has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #44)
2. Your PR will be reviewed by the ThinknetCollective maintainers

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