feat(fusion_plating_shopfloor): workspace sign-off confirms saved signature, draws only when absent

onFinishStep: if the user has a saved Plating Signature, show FpSignatureConfirm
(one-tap, preview); otherwise open the draw-pad. Factored _openSignaturePad +
_commitSignOff (sends null data URI when using the saved signature).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

fusion_plating/fusion_plating_shopfloor/static/src/js/job_workspace.js

@@ -25,6 +25,7 @@ import { useService } from "@web/core/utils/hooks";
 import { WorkflowChip } from "./components/workflow_chip";
 import { GateViz } from "./components/gate_viz";
 import { FpSignaturePad } from "./components/signature_pad";
+import { FpSignatureConfirm } from "./components/signature_confirm";
 import { FpHoldComposer } from "./components/hold_composer";
 import { FpTabletLock } from "./tablet_lock";
 import { FpRackPartsDialog } from "./rack_parts_dialog";
@@ -38,7 +39,7 @@ import { FileModel } from "@web/core/file_viewer/file_model";
 export class FpJobWorkspace extends Component {
     static template = "fusion_plating_shopfloor.JobWorkspace";
     static props = ["*"];
-    static components = { WorkflowChip, GateViz, FpSignaturePad, FpHoldComposer, FpTabletLock, FpRackPartsDialog, FpDamageDialog, FpFinishBlockDialog, RackingPanel, FpMovePartsDialog };
+    static components = { WorkflowChip, GateViz, FpSignaturePad, FpSignatureConfirm, FpHoldComposer, FpTabletLock, FpRackPartsDialog, FpDamageDialog, FpFinishBlockDialog, RackingPanel, FpMovePartsDialog };
 
     setup() {
         this.notification = useService("notification");
@@ -363,14 +364,41 @@ export class FpJobWorkspace extends Component {
 
     async onFinishStep(step) {
         if (step.requires_signoff) {
+            if (this.state.data.user_has_plating_signature) {
+                // One-tap confirm with a preview of the saved Plating Signature.
+                this.dialog.add(FpSignatureConfirm, {
+                    title: `Sign to finish ${step.name}`,
+                    contextLabel: `${this.state.data.job.display_wo_name} · Step ${step.sequence_display}: ${step.name}`,
+                    signatureUrl: this.state.data.user_plating_signature,
+                    onConfirm: () => this._commitSignOff(step, null),   // use saved sig
+                    onRedraw: () => this._openSignaturePad(step),       // draw a new one
+                });
+            } else {
+                // First time — draw once; the backend persists it to the
+                // user's Plating Signature so later sign-offs are one-tap.
+                this._openSignaturePad(step);
+            }
+            return;
+        }
+        // Plain finish — route through /fp/workspace/finish_step which
+        // returns structured errors so we can show the FpFinishBlockDialog
+        // for required-inputs failures (with manager bypass option).
+        await this._callFinishStep(step, /* bypass */ false);
+    }
+
+    _openSignaturePad(step) {
         this.dialog.add(FpSignaturePad, {
             title: `Sign to finish ${step.name}`,
             contextLabel: `${this.state.data.job.display_wo_name} · Step ${step.sequence_display}: ${step.name}`,
-                onSubmit: async (dataUri) => {
+            onSubmit: (dataUri) => this._commitSignOff(step, dataUri),
+        });
+    }
+
+    async _commitSignOff(step, dataUri) {
         try {
             const res = await fpRpc("/fp/workspace/sign_off", {
                 step_id: step.id,
-                            signature_data_uri: dataUri,
+                signature_data_uri: dataUri,   // null -> backend uses the saved signature
             });
             if (res && res.ok) {
                 this.notification.add("Step signed off and finished.", { type: "success" });
@@ -381,14 +409,6 @@ export class FpJobWorkspace extends Component {
         } catch (err) {
             this.notification.add(err.message, { type: "danger" });
         }
-                },
-            });
-            return;
-        }
-        // Plain finish — route through /fp/workspace/finish_step which
-        // returns structured errors so we can show the FpFinishBlockDialog
-        // for required-inputs failures (with manager bypass option).
-        await this._callFinishStep(step, /* bypass */ false);
     }
 
     async _callFinishStep(step, bypassRequiredInputs) {