Add CLAUDE.md and remove release freeze (#1211)

## Summary
- Adds a `CLAUDE.md` file documenting build/test commands, project
structure, and coding conventions
- Captures common PR check pitfalls: DCO sign-off, NEXT_CHANGELOG /
`NO_CHANGELOG=true`, release freeze override, and GitHub account
selection (non-EMU)
- Removes release freeze after 3.2.1 release
(`development/.release-freeze.json` set to `freeze: false`)

NO_CHANGELOG=true

## Test plan
- [ ] Verify CLAUDE.md renders correctly on GitHub
- [ ] Confirm CI checks pass (DCO, changelog)
- [ ] Verify release freeze is disabled after merge

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

---------

Signed-off-by: Vikrant Puppala <vikrant.puppala@databricks.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: vikrantpuppala

CLAUDE.md

@@ -0,0 +1,46 @@
+# CLAUDE.md — Databricks JDBC Driver
+
+## Build & Test
+
+- **Build**: `mvn clean install -DskipTests`
+- **Run tests**: `mvn test`
+- **Run a single test**: `mvn test -pl . -Dtest=ClassName#methodName`
+- **Format code**: `mvn spotless:apply` (also runs automatically during build/test)
+- **JDK**: Java 11+
+
+## Project Structure
+
+- `src/main/java/com/databricks/jdbc/` — main driver source
+- `src/test/java/com/databricks/jdbc/` — unit and integration tests
+- `development/.release-freeze.json` — controls release freeze state
+
+## PR Checks — Common Pitfalls
+
+### 1. DCO Sign-off (required)
+
+Every commit must include a `Signed-off-by` line. Always use the `-s` flag:
+
+```bash
+git commit -s -m "Your commit message"
+```
+
+### 2. NEXT_CHANGELOG.md (required unless opted out)
+
+The `check-next-changelog` CI check verifies that either:
+
+- `NEXT_CHANGELOG.md` is modified in the PR, **or**
+- The PR description body contains `NO_CHANGELOG=true`
+
+For internal refactors, test-only changes, or fixes that don't need a changelog entry, add `NO_CHANGELOG=true` to the PR description.
+
+### 3. Release Freeze
+
+When a release freeze is active (`development/.release-freeze.json` has `"freeze": true`), PRs are blocked from merging. To override, add `OVERRIDE_FREEZE=true` to the PR description. Use this only when the merge is necessary during the freeze window.
+
+### 4. GitHub Account (non-EMU)
+
+Users may have multiple GitHub accounts (e.g., an EMU/enterprise account and a personal account). Pushing and creating PRs on this repo requires the **non-EMU** account. Check the active account with `gh auth status` and switch if needed with `gh auth switch --user <username>`.
+
+## Coding Conventions
+
+- Follow the [Google Java Style Guide](https://google.github.io/styleguide/javaguide.html)

development/.release-freeze.json

@@ -1,4 +1,3 @@
 {
-  "freeze": true,
-  "reason": "Release version 3.2.1"
+  "freeze": false
 }