ci: Add CLA Assistant workflow (#61)

.github/workflows/cla.yml

@@ -0,0 +1,46 @@
+name: CLA Assistant
+on:
+  issue_comment:
+    types: [created]
+  pull_request_target:
+    types: [opened, closed, synchronize]
+
+permissions:
+  actions: write
+  contents: write
+  pull-requests: write
+  statuses: write
+
+jobs:
+  cla:
+    runs-on: ubuntu-latest
+    steps:
+      - name: CLA Assistant
+        if: (github.event.comment.body == 'I have read the CLA Document and I hereby sign the CLA' || github.event_name == 'pull_request_target')
+        uses: contributor-assistant/github-action@v2.6.1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PERSONAL_ACCESS_TOKEN: ${{ secrets.PERSONAL_ACCESS_TOKEN }}
+        with:
+          path-to-signatures: 'signatures.json'
+          path-to-document: 'https://github.com/Aryan-Raj3112/episteme/blob/main/CLA.md'
+          branch: 'cla-signatures'
+          allowlist: 'bot*,dependabot*'
+
+          # Custom messages
+          custom-notsigned-prcomment: |
+            Thank you for your contribution! Before we can merge this, you need to sign our 
+            [Contributor License Agreement](https://github.com/Aryan-Raj3112/episteme/blob/main/CLA.md).
+            
+            **Why?** Episteme is dual-licensed (open-source AGPL + commercial). The CLA ensures 
+            we have permission to use your contribution in both versions.
+            
+            To sign, please reply with a comment containing exactly:
+            ```
+            I have read the CLA Document and I hereby sign the CLA
+            ```
+            
+            You only need to do this once. It covers all future contributions.
+
+          custom-pr-sign-comment: 'I have read the CLA Document and I hereby sign the CLA'
+          custom-allsigned-prcomment: 'All contributors have signed the CLA. ✅'