fix(conversations): apply the selected preset's parameters when creating a conversation

[AndyScherzinger]

The conversation creation screen sent only the preset identifier to the creation endpoint. That
endpoint derives just the conversation attributes from it and stores whatever parameters the request
carried, so the parameters of the selected conversation type never arrived:

• Voice rooms were created neither listable nor expiring.
• Channels and announcements granted call and media permissions (372) instead of reactions only
  (257), which contradicts our own nc_channel_description string.
• The "allow guests" switch had no effect whatsoever: roomType was hardcoded to group, so no
  public conversation was ever created, and the password was then set on a private one.
• The administrator configured defaults never reached a created conversation.

On top of that the redundant POST /listable after creation is gone, the voice room type is hidden
where calls are disabled server wide, and servers without conversation-creation-all are served by
follow-up requests instead of silently losing the participants, the description and the listable
state.

This is the first of three stacked PRs; the conversation types themselves move to the presets
endpoint in the follow-up.

🖼️ Screenshots

No visual change other than the voice room type being hidden where calls are disabled server wide,
so no before/after shots.

🚧 TODO

• nothing outstanding

🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included or not needed
• 🔖 Capability is checked or not needed
• 🔙 Backport requests are created or not needed: /backport to stable-xx.x
• 📅 Milestone is set
• 🌸 PR title is meaningful (if it should be in the changelog: is it meaningful to users?)

Capabilities checked: conversation-creation-all, conversation-creation-password (added here),
conversation-presets, announcement-preset and config => call => enabled.

🤖 AI (if applicable)

• The content of this PR was partly or fully generated using AI

🤖 Generated with Claude Code

https://claude.ai/code/session_014YnDswTbCmRrVETnwE4twB

[github-actions]

APK file: https://github.com/nextcloud/talk-android/actions/runs/33898044737/artifacts/9946813233
To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.
(please click on link to get QR code displayed)

[github-actions]

APK file: https://github.com/nextcloud/talk-android/actions/runs/33950426057/artifacts/9964745178
To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.
(please click on link to get QR code displayed)

[github-actions]

APK file: https://github.com/nextcloud/talk-android/actions/runs/33961731118/artifacts/9968253024
To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.
(please click on link to get QR code displayed)