refactor(connectors): drop dead CLI command field after pi-mono migration

The CLI-adapter era `connector.command` field became vestigial once every
provider dispatch went through pi-ai. The schema still required a non-empty
command, so onboarding saveConnector silently rejected every Pi Mono row
(which carries an empty default). Remove the field from the payload chain
(renderer → IPC schema → DB CRUD → run dispatch → worker job), narrow
RunJob.taskId to match EnqueueRunPayload, and drop the dead helper plus
its test. Schema column stays NOT NULL for DB compatibility; seedConnectors
writes a literal empty string so no migration is needed.

src/shared/contracts/schemas-company.ts

@@ -53,7 +53,6 @@ export type ConnectorId = z.infer<typeof connectorIdEnum>;
 
 export const connectorInputSchema = z.object({
   id: connectorIdEnum,
-  command: z.string().min(1),
   model: z.string().nullable().optional(),
   envBindingText: z.string().default(""),
   notes: z.string().default(""),