Add Trailer API lifecycle collection

[roncodes]

Summary

Trailer API lifecycle coverage for the first-class Trailer feature (fleetbase/fleetops#309).

• Trailer resource definition and object schema, including the additive relation identifiers (category_id, vendor_id, warranty_id, photo_id, vehicle_id), the always-present equipment, devices and connections collections, and the sanitized telematics snapshot.
• Lifecycle requests: create, query, retrieve, update, track, attach, detach, connection history, vehicle trailer list, and delete.
• Trailer Device and Equipment attachment, detachment, reassignment, verification and cleanup through the polymorphic attachable_type contract.
• Query parameter documentation for the supported filters and with expansions.

Assertions

Assertions match the shipped responses: public IDs only (no *uuid keys), attachment_state, vehicle_id/trailer_id on connections, the attached state exposed by GET /vehicles/{id}/trailers, stored coordinates and connectivity after tracking, and the telematics snapshot without device identifiers. Every scenario captures its own identifiers into environment variables and cleans up the resources it creates.

Validation

• npm run postman:lint: 5 collections validated, Fleetbase API 219 requests, 0 errors, 0 warnings.
• The lifecycle was exercised against a local Fleetbase stack with the finalized fleetops branch (create, retrieve with expansions, attach with position conflicts and idempotent re-attach, detach twice, connections, vehicle trailer list, track including stale and null-island observations, delete guard).
• Add first-class Trailer operations fleetops#309 pins its contract workflow to this revision (0590548).

Related PRs

• Fleet-Ops: Add first-class Trailer operations fleetops#309
• fleetops-data: Add first-class Trailer data models fleetops-data#75
• fleetbase.io: Document first-class Trailer operations fleetbase.io#96