…controller Package

Backport of #3333 onto release-1.5.

spec.components.platform.values.backupStorage on the
cozystack.cozystack-platform Package -- the documented override path for
the cozy-default BackupClass -- never reached the
backupstrategy-controller HelmRelease, so endpoint/region/bucketName
overrides for an external S3 were silently dropped (#3245). The platform
chart now forwards the block into the emitted child Package the same way
bundles/iaas.yaml forwards kubevirt and gpu-operator values. The 4-arg
cozystack.platform.package helper the change needs already exists on this
branch.

Two conflicts, both from unrelated drift in the touched files rather than
from the fix:

  * platform values.yaml -- main's hunk carries `monitoring.rootEnabled`
    alongside `backupStorage`. That key belongs to the tenant-root
    monitoring gate (#3181), which is not on release-1.5 and whose absence
    nothing here depends on, so only the backupStorage block is taken.

  * docs/operations/backup-classes.md -- the conflicting hunk rewrites the
    Postgres upgrade note for the CNPG barman plugin migration
    (spec.plugins + ObjectStore), which is 1.6 behaviour. release-1.5 still
    renders spec.backup.barmanObjectStore, so this branch keeps its own
    prose. The rest of the doc update applied cleanly and was checked
    claim-by-claim against this branch rather than assumed: the
    helmrelease-interval flag, the cozy-backup-controller namespace, the
    cozystack_backup_credentials_projection_* metric names and the
    provisionBucket / namespace / bucketName knobs the new table rows
    describe all exist here.

Assisted-By: Claude <noreply@anthropic.com>
Signed-off-by: Myasnikov Daniil <myasnikovdaniil2001@gmail.com>
(cherry picked from commit 13aa3cb31e71f89e6ffe2a5fcd0fcd9e3f80e970)