Allow configuring a dedicated OCR user

[R0Wi]

Summary

• Fixes Automated OCR operations are attributed to the impersonated file owner (audit-trail / accountability concern) #385: automated OCR operations were always attributed to the impersonated file owner, making them indistinguishable from manual edits in the version history and activity log.
• Adds an optional global admin setting ("OCR user"). If left empty (default), behavior is unchanged and the file owner is impersonated as before. If set, the whole OCR run (user session, filesystem access, resulting file version/label) runs as that configured user instead.
• Success notifications are still always sent to the file owner. If the configured user doesn't exist, the app logs a warning and falls back to the file owner.

Changes

• lib/Model/GlobalSettings.php: new nullable processingUserId setting.
• lib/Service/OcrService.php: reads global settings before initializing the user environment, determines the processing uid (configured user, or file owner as fallback), and separates the "processing user" from the "owner" (used for notifications).
• lib/Service/GlobalSettingsService.php: empty string now maps to null for nullable string settings, mirroring the existing 0 -> null behavior for ints.
• lib/Controller/GlobalSettingsController.php: trims and normalizes blank input to null.
• src/components/GlobalSettings.vue: new text input for the OCR user, saved on blur.
• README.md: documents the new setting and its permission requirements.

Test plan

• Added OcrServiceTest::testRunsOcrProcessWithConfiguredProcessingUser and testFallsBackToFileOwnerIfConfiguredProcessingUserDoesNotExist.
• Updated GlobalSettingsServiceTest and GlobalSettingsControllerTest for the new setting (including null/blank handling).
• Added Vue tests for the new input in GlobalSettings.spec.js.
• Ran full PHPUnit suite against a real Nextcloud (master) checkout — all workflow_ocr tests pass except 4 pre-existing/environmental failures unrelated to this change (missing Imagick extension, running as root).
• Ran npm run test:unit (53 passed), npm run lint, and composer cs:check — all clean, no new issues introduced.

---

Generated by Claude Code

[Copilot]

Pull request overview

Adds an optional global “OCR user” setting so automated OCR runs (filesystem session, version author/activity attribution) can be executed as a dedicated service account instead of impersonating the file owner, addressing audit-trail/accountability concerns from #385 while keeping notifications targeted to the file owner.

Changes:

• Introduces a new nullable global setting (processingUserId) and normalizes blank input to null across controller/service/UI.
• Updates OCR execution to choose a “processing user” (configured user or fallback to owner) while keeping the “owner user” for notifications.
• Adds/updates PHPUnit + Vue unit tests covering configured-user behavior and fallback when the configured user does not exist.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
lib/Model/GlobalSettings.php	Adds nullable processingUserId global setting.
lib/Service/GlobalSettingsService.php	Maps empty-string string settings to null when the property is nullable.
lib/Controller/GlobalSettingsController.php	Trims/normalizes processingUserId input to null when blank.
lib/Service/OcrService.php	Determines processing UID from global setting and separates processing user vs owner for notifications.
src/components/GlobalSettings.vue	Adds admin UI input for “OCR user” and saves normalized values.
src/test/components/GlobalSettings.spec.js	Adds Vue tests for trimming and nulling the new setting.
tests/Unit/Service/GlobalSettingsServiceTest.php	Updates unit tests for new nullable string setting + empty-string handling.
tests/Unit/Controller/GlobalSettingsControllerTest.php	Adds controller tests for trimming and mapping blank inputs to null.
tests/Unit/Service/OcrServiceTest.php	Adds tests for running as configured processing user and fallback when missing.
README.md	Documents the new “OCR user” setting and required permissions/fallback behavior.

Suppressed comments (1)

lib/Service/OcrService.php:261

• The PHPDoc line has an extra leading "" (" * @PARAM"), which makes the docblock malformed and can confuse tooling/IDEs.

	/**
	 * * @param string $uid 	The userId to run the OCR process with
	 */