fix(volumes): Fix volume credential handling for mounted volumes

[xd003]

Existing volume operations were unnecessarily decrypting stored credentials even when credentials were not required. As a result, health checks, file browsing, and unmount operations could fail when stored SMB, WebDAV, or SFTP credentials were unavailable or could not be decrypted, even though the volume was already mounted and could still be inspected or unmounted.

Credential handling during volume updates also had two issues:

• Updating a volume could discard unchanged stored configuration fields.
• Replacement credentials were not always prepared before the existing mount was unmounted.
• Connection tests could run against encrypted stored values instead of resolved credentials.

This change:

• Avoids resolving volume credentials for operations that only inspect or unmount an existing mount.
• Preserves unchanged stored configuration during updates.
• Resolves and prepares replacement credentials before unmounting the current volume.
• Resolves stored secrets before testing connections.
• Applies consistently to both controller-local and local-agent execution paths.
• Restores reliable handling of existing SMB, WebDAV, and SFTP credentials without exposing or unnecessarily decrypting secrets.

This keeps inspection and cleanup operations available even when credential decryption is not required, while ensuring connection and replacement operations receive usable plaintext credentials.

Fixes #1064

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

• Configuration used: Organization UI
• Review profile: CHILL
• Plan: Advanced
• Run ID: 99579dce-6713-4de4-af54-c369e477fb72

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

• Autopilot · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[xd003]

@nicotsx Hello, can you review this one, it fixes the linked issue.