fix(skills): validate installs before writing

Preserve bundled files and normalize fallback names across skill installation paths.

Validate complete batches before writing and reject existing targets to avoid partial installs.

Keep project metadata and make folder selection tolerant of casing and cancelled dialogs.

server/modules/providers/provider.routes.ts

@@ -197,6 +197,7 @@ const parseProviderSkillCreatePayload = (payload: unknown): ProviderSkillCreateI
           content: body.content,
           directoryName: body.directoryName,
           fileName: body.fileName,
+          files: body.files,
         }]
       : null;