fix(migration): support the public OCP\DB\Schema API

Nextcloud 35 replaced the Doctrine DBAL return types of ISchemaWrapper
with the public OCP\DB\Schema interfaces (server#63013). Bump the
nextcloud/ocp dev dependency so the shipped OCP stubs carry the new
signatures instead of shadowing the server ones with the pre-35
declarations, and point the changeSchema() @throws at the OCP
SchemaException that ISchemaWrapper::getTable() now raises.

The composer platform requirement is raised to PHP 8.3 to match the
minimum of Nextcloud 35, which nextcloud/ocp now also requires.

That @throws was the only docblock-only reference to an undefined class
left in the code base, so the UndefinedDocblockClass suppression no
longer suppresses anything and Psalm reports it as an
UnusedIssueHandlerSuppression. Psalm counts suppressions per errorLevel
filter rather than per referencedClass, so the whole handler has to go.
Undefined classes referenced outside docblocks stay covered by the
UndefinedClass handler.

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>
Assisted-by: Claude Code:claude-opus-5[1m]

Author: AndyScherzinger

composer.json

@@ -25,7 +25,7 @@
 			"bamarni/composer-bin-plugin": true
 		},
 		"platform": {
-			"php": "8.2"
+			"php": "8.3"
 		}
 	},
 	"scripts": {