feat: use packageManager from package.json as default bun version (#152)

* Initial plan

* feat: make packageManager from package.json the default bun version

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

* test: improve cross-platform compatibility and cleanup in utils tests

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

* docs: update README to document automatic package.json version detection

Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>

* conflicts

* ci: setup-bun-from-package-json-without-specified-field

* ci: setup-bun-from-package-json-without-specified-field

* ci: no cache

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: xhyrom <56601352+xhyrom@users.noreply.github.com>
Co-authored-by: Jozef Steinhübl <contact@xhyrom.dev>

.github/workflows/test.yml

@@ -32,6 +32,8 @@ jobs:
 
       - name: Setup Bun
         uses: ./
+        with:
+          no-cache: true
 
       - name: Install dependencies
         run: bun install
@@ -77,6 +79,7 @@ jobs:
         id: setup_bun
         with:
           bun-version: ${{ matrix.bun-version }}
+          no-cache: true
 
       - name: ▶️ Run Bun
         id: run_bun
@@ -154,6 +157,53 @@ jobs:
         uses: ./
         with:
           bun-version-file: ${{ matrix.file.file }}
+          no-cache: true
+
+      - name: ⚖️ Compare versions
+        uses: ./.github/actions/compare-bun-version
+        with:
+          bun-version: "1.1.0"
+
+  setup-bun-from-package-json-without-specified-field:
+    name: setup-bun from (${{ matrix.os }}, ${{ matrix.file.name }}) without specified field
+    runs-on: ${{ matrix.os }}
+    continue-on-error: true
+    needs: [remove-cache, tests]
+    strategy:
+      matrix:
+        os:
+          - ubuntu-latest
+          - macos-latest
+          - windows-latest
+          - windows-11-arm
+
+        file:
+          - name: package.json (packageManager bun@1.1.0)
+            file: package.json
+            run: |
+              echo "$(jq '. += {"packageManager": "bun@1.1.0"}' package.json)" > package.json
+
+          - name: package.json (packageManager yarn@bun@1.1.0)
+            file: package.json
+            run: |
+              echo "$(jq '. += {"packageManager": "yarn@bun@1.1.0"}' package.json)" > package.json
+
+          - name: package.json (engines bun@1.1.0)
+            file: package.json
+            run: |
+              echo "$(jq '.engines = {"bun": "1.1.0"}' package.json)" > package.json
+
+    steps:
+      - name: 📥 Checkout
+        uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955 # v4
+
+      - name: 📄 Setup file
+        run: ${{ matrix.file.run }}
+
+      - name: 🛠️ Setup Bun
+        uses: ./
+        with:
+          no-cache: true
 
       - name: ⚖️ Compare versions
         uses: ./.github/actions/compare-bun-version