feat(upload): add --into-album to all upload subcommands

[Digital39999]

The --into-album flag was wired separately in from-folder, from-icloud, and from-picasa, while from-immich and from-google-photos lacked it entirely. This hoists it onto the upload parent so all five subcommands get it, and removes the duplicated wiring from each adapter.

The override now runs in handleGroup instead of inside each adapter's Browse loop. Same place in the pipeline, just centralized.

Validation for --into-album + --folder-as-album is preserved on the folder-based subcommands.

Config files need a small update: if you had into-album under [upload.from-folder] (or icloud/picasa), move it to [upload]. The env var is now IMMICH_GO_UPLOAD_INTO_ALBUM.

[Copilot]

Pull request overview

This PR centralizes the --into-album upload behavior by moving the flag to the upload parent command and applying the album override in the shared upload pipeline, so all upload subcommands can use it consistently.

Changes:

• Hoist --into-album to the upload parent command and apply the override in UpCmd.handleGroup.
• Remove duplicated --into-album wiring from folder and Google Photos adapters.
• Update documentation for CLI usage, env vars, and config location ([upload].into-album and IMMICH_GO_UPLOAD_INTO_ALBUM).

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
docs/upload-commands-overview.md	Documents --into-album for from-immich transfers.
docs/environment.md	Moves env var mapping to IMMICH_GO_UPLOAD_INTO_ALBUM and removes per-subcommand variants.
docs/configuration.md	Moves config key to [upload].into-album and updates examples.
docs/commands/upload.md	Adds --into-album destination option + example for upload from-immich.
app/upload/upload.go	Adds ImportIntoAlbum to UpCmd and registers --into-album as a persistent upload flag.
app/upload/run.go	Applies the album override centrally in handleGroup.
adapters/googlePhotos/googlephotos.go	Removes adapter-local forced album override; keeps album derivation when syncing albums.
adapters/googlePhotos/cmdFromGooglePhotos.go	Removes ImportIntoAlbum field from TakeoutCmd.
adapters/folder/run.go	Preserves mutual exclusion validation via flag lookup rather than adapter field.
adapters/folder/commands.go	Removes adapter-local --into-album flag registration.