feat: show live build version in web UI

- /api/version returns version, commitSha, buildDate, trashRetentionDays
- CI passes COMMIT_SHA (full), BUILD_DATE and VERSION (git tag) as
  docker build args; Dockerfile bakes them as env
- sidebar footer shows version/sha linked to the Gitea commit
- admin System tab shows version, commit link, build date, trash retention

lib/api-zod/src/generated/api.ts

@@ -17,6 +17,18 @@ export const HealthCheckResponse = zod.object({
 })
 
 
+/**
+ * Returns the running build version, commit SHA and build date
+ * @summary Build version information
+ */
+export const GetVersionResponse = zod.object({
+  "version": zod.string(),
+  "commitSha": zod.string().nullish(),
+  "buildDate": zod.string().nullish(),
+  "trashRetentionDays": zod.number().optional()
+})
+
+
 /**
  * @summary List all tools
  */