ci: skip builds for [skip ci] commits and markdown changes

Adds [skip ci] detection to prevent unnecessary workflow runs when builds are not needed.

Excludes markdown files from triggering iOS builds to reduce resource usage for documentation changes.

Removes redundant node_modules caching step in Android workflow since Bun handles dependency management efficiently.

.github/workflows/build-android.yml

@@ -13,6 +13,7 @@ on:
 
 jobs:
   build-android:
+    if: (!contains(github.event.head_commit.message, '[skip ci]'))
     runs-on: ubuntu-24.04
     name: 🏗️ Build Android APK
     permissions:
@@ -46,16 +47,6 @@ jobs:
             ${{ runner.os }}-${{ runner.arch }}-bun-develop
             ${{ runner.os }}-bun-develop
 
-      - name: 💾 Cache node_modules
-        uses: actions/cache@0400d5f644dc74513175e3cd8d07132dd4860809 # v4.2.4
-        with:
-          path: node_modules
-          key: ${{ runner.os }}-${{ runner.arch }}-modules-latest-develop-${{ hashFiles('bun.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-${{ runner.arch }}-modules-latest-develop
-            ${{ runner.os }}-${{ runner.arch }}-modules-develop
-            ${{ runner.os }}-modules-develop
-
       - name: 📦 Install dependencies and reload submodules
         run: |
           bun install --frozen-lockfile