fix(files): invalidate cached storage availability after updates

[joshtrichards]

Summary

Fix stale storage availability reads by invalidating StorageGlobal after Storage::setAvailability() updates the database.

Problem

OC\Files\Cache\Storage::setAvailability() persists availability changes to the storages table, but StorageGlobal can continue returning a cached storage record within the same process. This can leave available and last_checked stale after a successful update.

Changes

• clear cached storage info after availability updates
• add targeted cache invalidation helpers to StorageGlobal
• clear both internal caches in StorageGlobal::clearCache()
• add a DB-backed regression test covering both string-id and numeric-id lookups
• refresh the class docblocks for Storage and StorageGlobal

Why

This keeps in-process storage metadata reads consistent with the persisted database state and avoids stale availability reads after state transitions.

Testing

Added a regression test that primes the global storage cache, updates availability, and verifies that both string-id and numeric-id lookups observe the updated state.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI [used to generate the baseline tests]