CI: add platform filter for workflow_dispatch

Both build and toolchain workflows now accept an optional 'platform'
input when triggered manually.  If set, only that platform runs.
If empty (default), all platforms run as before.

Usage:
  gh workflow run build.yml -f platform=hi3516cv100_lite
  gh workflow run toolchain.yml -f platform=hi3516cv100_lite

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: widgetii

.github/workflows/build.yml

@@ -6,6 +6,11 @@ on:
   schedule:
     - cron: '30 22 * * *'
   workflow_dispatch:
+    inputs:
+      platform:
+        description: 'Build only this platform (e.g. hi3516cv100_lite). Empty = all.'
+        required: false
+        default: ''
 
 env:
   TAG_NAME: latest
@@ -161,6 +166,8 @@ jobs:
           - gk7205v200_ultimate
           - gk7205v300_ultimate
 
+    if: ${{ !github.event.inputs.platform || matrix.platform == github.event.inputs.platform }}
+
     steps:
       - name: Checkout source
         uses: actions/checkout@v4

.github/workflows/toolchain.yml

@@ -1,6 +1,11 @@
 name: toolchain
 on:
   workflow_dispatch:
+    inputs:
+      platform:
+        description: 'Build only this platform (e.g. hi3516cv100_lite). Empty = all.'
+        required: false
+        default: ''
 
 env:
   TAG_NAME: toolchain
@@ -63,6 +68,8 @@ jobs:
           - xm510_lite
           - xm530_lite
 
+    if: ${{ !github.event.inputs.platform || matrix.platform == github.event.inputs.platform }}
+
     steps:
       - name: Checkout source
         uses: actions/checkout@v4