Add LoraTap QCSC500W-V2N2 product ID (#5762)

* feat(devices): Add LoraTap QCSC500W-V2N2

Recognize product ID nnfrmb3val45av1n and map its DP 8 back value to the existing backward mode.

Co-Authored-By: OpenAI Codex <noreply@openai.com>

* Remove control_back_mode mappings from YAML

Removed mapping for control_back_mode to avoid confusion.
I think the original intention was to record the values for future reference, but now that an inconsistency between devices is found, there is no real future for this attribute.

---------

Co-authored-by: OpenAI Codex <noreply@openai.com>
Co-authored-by: Jason Rumney <make-all@users.noreply.github.com>

custom_components/tuya_local/devices/loratap_curtain_switch_QCSC400ZB-V2.yaml

@@ -3,6 +3,9 @@ products:
   - id: qa8s8vca
     manufacturer: LoraTap
     model: QCSC400ZB-V2
+  - id: nnfrmb3val45av1n
+    manufacturer: LoraTap
+    model: QCSC500W-V2N2
   - id: cqcew2xvoqjdaixe
     manufacturer: LoraTap
     model: SC400W
@@ -23,11 +26,6 @@ entities:
       - id: 8
         name: control_back_mode
         type: string
-        mapping:
-          - dps_val: forward
-            value: forward
-          - dps_val: backward
-            value: backward
       - id: 10
         name: tr_timecontrol
         type: integer