feat: make preview conversion timeout and max file size configurable

[juliusknorr]

Attempt to implement with Claude Sonnet 4.6 and a custom agent definition, therefore collecting my personal feedback on that a bit here:

• Prompt was rather simple with more context in the github issue: Create a branch, Implement the feature described in https://github.com/nextcloud/richdocuments/issues/5404 and open a pull request for it
• Did one manual fixup 1f269e6 but otherwise this is good 👍
• Not a fan of the changes summary in the pr message, could be improved in prompting
• It needed some guidance to run phpunit tests with the xml configuration file
• Asked to cover this with phpunit tests 2a2ed3e

Summary

Fixes #5404

Adds two new configurable options for preview conversion:

• Timeout: The timeout (in seconds) for preview conversion requests to Collabora. Defaults to 5 seconds.
• Max file size: Files larger than this limit are skipped and no preview is generated. Defaults to 100 MB.

Both options can be set via occ config:app:set:

occ config:app:set richdocuments preview_conversion_timeout --type integer --value 10
occ config:app:set richdocuments preview_conversion_max_filesize --type integer --value 52428800

Changes

• Added PREVIEW_CONVERSION_TIMEOUT and PREVIEW_CONVERSION_MAX_FILESIZE constants + getter methods to AppConfig
• Office::getThumbnail now skips conversion when file size exceeds the configured limit
• RemoteService::convertFileTo passes the configured timeout to the HTTP client
• RemoteService::convertTo accepts a $timeout parameter (defaults to REMOTE_TIMEOUT_DEFAULT for non-preview callers)
• Documentation updated in docs/app_settings.md

[Copilot]

Pull request overview

This PR implements configurable timeout and maximum file size settings for preview conversion operations in the Nextcloud Richdocuments app. The changes address issue #5404 by allowing administrators to customize preview conversion behavior via OCC commands.

Changes:

• Added two new configuration options: preview_conversion_timeout (default: 5 seconds) and preview_conversion_max_filesize (default: 100 MB)
• Modified the preview generation logic to skip files exceeding the configured size limit
• Updated the conversion service to use the configured timeout for preview requests while maintaining backward compatibility for other conversion operations

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
lib/AppConfig.php	Adds constants and getter methods for the two new configuration options with appropriate defaults
lib/Service/RemoteService.php	Adds timeout parameter to convertTo() method and passes configured timeout from convertFileTo()
lib/Preview/Office.php	Implements file size check before attempting preview conversion with debug logging
docs/app_settings.md	Documents the new configuration options with usage examples
tests/lib/AppConfigTest.php	Adds unit tests for the new AppConfig getter methods
tests/lib/Preview/OfficeTest.php	Adds unit tests for the new file size checking behavior in preview generation

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[emberfiend]

/backport to stable31 please