chore: fixed vulneribilities

[contentstackMridul]

Summary

• Upgraded fastify from ^4.21.0 to ^5.7.4 to address known vulnerabilities in the v4 release line
• Upgraded all companion @fastify/* plugins and fastify-plugin to their Fastify v5-compatible major versions, as the v4-era plugins declare fastify: '4.x' in their metadata and are rejected at startup by Fastify v5 (FST_ERR_PLUGIN_VERSION_MISMATCH)

Package	Before	After
fastify	^4.21.0	^5.7.4
@fastify/cors	^8.3.0	^11.0.0
@fastify/rate-limit	^9.1.0	^10.0.0
@fastify/swagger	^8.8.0	^9.0.0
@fastify/swagger-ui	^3.0.0	^5.0.0
fastify-plugin	^4.5.1	^5.0.0

No source code changes were required -- all existing API patterns (.listen() signature, JSON schemas, logger config, reply handling) were already compatible with Fastify v5.

Note: @fastify/cors v11 changed default allowed methods to GET,HEAD,POST (previously all methods). This has no impact on our current routes (all GET/POST), but any future PUT/PATCH/DELETE routes will require explicit methods configuration in the CORS options.

Test Plan

• Server boots without errors
• All existing endpoints respond correctly (/health, /health/views, /sync-github-repo, /get-preview-data)
• Swagger UI loads at /documentation
• All 15 unit tests pass
• npm audit reports 0 vulnerabilities