[maci0]

Add an optional Phobos ZIP updater using the published source-built Cortex-A7 package:
https://github.com/maci0/phobos/releases/download/v0.3.0/phobos-arm-linux-musleabihf.zip

The existing ZIP backend selects the first GitHub asset, which is unsafe for Phobos's multi-architecture releases. Add optional exact asset_name selection for refresh and rollback; named assets use the release tag for version matching. Missing or ambiguous assets fail before installation changes. Existing web/ZIP clients retain their first-asset behavior.

The phobos entry targets the dedicated /data/phobos directory and registers only when that directory exists. This adds no download, startup warning or daemon switch on normal Moonraker installations. It manages no services. Initial ZIP installation and explicit Phobos activation remain separate steps, documented in docs/PHOBOS.md. Older versioned-binary/manual installations are not migrated automatically.

Validation:

• 11 updater tests pass: architecture selection, missing/duplicate assets, release-tag versions, rollback selection, legacy behavior, optional-client startup and existing extraction safety.
• The published ZIP was downloaded and hash/CRC checked. Its executable matches the existing published source-built v0.3.0 binary exactly, and extraction through this bundled updater preserves executable mode and expected release metadata.
• No API daemon, Klipper service or printer was restarted for this change. A complete live self-update was not run.

Themes are independent in #103; this PR is based directly on 1.4.2 and contains no theme changes.