refactor: remove legacy statusCGC, statusVaccination, statusCgcProcess columns in favour of date fields

[nadavosa]

Context

PR #482 adds three new date-based columns to track when document statuses were set:

• statusVaccinationDate
• statusCGCApplicationDate
• statusCGCDate

The old enum-based columns are now redundant and should be removed once all code is adapted.

Old columns to remove

Column	Type	Replaced by
statusVaccination	DocumentStatusType	statusVaccinationDate (set = YES, null = NO)
statusCGC	DocumentStatusType	statusCGCDate / statusCGCApplicationDate
statusCgcProcess	VolunteerStateCGCType	statusCGCApplicationDate

Files to update (BE)

• src/data/entity/volunteer/volunteer.entity.ts — remove 3 @Column declarations
• src/server/utils/data/get-volunteer-patch-data.ts — remove statusCGC, statusVaccination, statusCgcProcess from patch object
• src/services/dto/dto-volunteer.ts — remove goodConductCertificate, measlesVaccination, statusCgcProcess from serializer
• src/services/dto/parser-volunteer-form.ts — remove statusVaccination/statusCGC mappings
• src/data/seeds/types.ts + volunteer.seed.ts — remove from seed types
• New migration — DROP COLUMN for all 3

Files to update (FE)

• src/components/Dashboard/Profile/sections/VolunteerProfileDocument/utils.ts — measlesVaccination name key
• PR feat: restore accompanying DTO for SDK 0.0.83 (re-do of #506) #512 may reference old fields via SDK — verify after SDK is updated

Dependency

Must be done after PR #482 is merged and deployed.