feat: add first-time contributor bot and PR size labeler

.github/workflows/first-time-contributor.yml

@@ -0,0 +1,38 @@
+name: First-Time Contributor Bot
+
+on:
+  issues:
+    types: [opened]
+  pull_request_target:
+    types: [opened]
+
+jobs:
+  greet:
+    runs-on: ubuntu-latest
+    permissions:
+      issues: write
+      pull-requests: write
+    steps:
+      - name: Greet First-Time Contributor
+        uses: actions/first-interaction@v1
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          issue-message: |
+            Welcome to OpenROAD! Thanks for opening your first issue.
+            To get started:
+            - Build Instructions: https://openroad.readthedocs.io/en/latest/contrib/BuildWithCMake.html
+            - Contribution Guide: https://openroad.readthedocs.io/en/latest/contrib/contributing.html
+
+            Please search existing issues before submitting to avoid duplicates.
+            A maintainer will get back to you soon!
+          pr-message: |
+            Welcome to OpenROAD! Thanks for opening your first PR.
+            Before we review:
+            - Contribution Guide: https://openroad.readthedocs.io/en/latest/contrib/contributing.html
+            - Build Instructions: https://openroad.readthedocs.io/en/latest/contrib/BuildWithCMake.html
+
+            Please ensure:
+            - CI passes
+            - Code is properly formatted
+            - Tests are included where applicable
+            A maintainer will review shortly!

.github/workflows/pr-labeler.yml

@@ -0,0 +1,26 @@
+name: PR Size Labeler
+
+on:
+  pull_request_target:
+    types: [opened, synchronize]
+
+jobs:
+  label:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    steps:
+      - name: Label PR Size
+        uses: codelytv/pr-size-labeler@v1
+        with:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          xs_label: size/XS
+          xs_max_size: 10
+          s_label: size/S
+          s_max_size: 100
+          m_label: size/M
+          m_max_size: 500
+          l_label: size/L
+          l_max_size: 1000
+          xl_label: size/XL
+          fail_if_xl: false