fix: Resolve duplicate sources jar entry breaking release (#449)

## Summary
- Rename shared `uni/src/main/scala/wvlet/uni/cli/CliEnv.scala` to
`CliEnvBase.scala` to avoid duplicate entry conflict with the
JVM-specific `CliEnv.scala` during `packageSrc`
- Add `release-note.yml` workflow to auto-generate GitHub release notes
on tag push

## Context
The v2026.1.0 release build failed with:
```
ZipException: duplicate entry: wvlet/uni/cli/CliEnv.scala
(uniJVM / Compile / packageSrc)
```

## Test plan
- [x] `./sbt uniJVM/compile` succeeds locally
- [ ] CI passes
- [ ] After merge, re-tag and verify release pipeline completes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: xerial

.github/workflows/release-note.yml

@@ -0,0 +1,18 @@
+name: Release Note
+
+on:
+  push:
+    tags:
+      - v*
+  workflow_dispatch:
+
+jobs:
+  release:
+    name: Create a new release note
+    runs-on: ubuntu-latest
+    steps:
+      - name: Create a release note
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          gh release create "$GITHUB_REF_NAME" --repo="$GITHUB_REPOSITORY" --generate-notes