Add documentation, config template and ownership files

- Rewrite README.md: build+licence badges, Overview with Key Features,
  standard sections (Prerequisites, Downloading, Check dependencies,
  Building the Sample, Deploying to CICS Liberty JVM server with 3
  deployment methods, Running, Troubleshooting, License, Contributing)
- Update build commands: clean build (Gradle), clean verify (Maven)
- Update prerequisites: CICS TS V6.1+, Java 17+, Jakarta EE 10
- Add CODEOWNERS replacing MAINTAINERS.md (Issue: old convention)
- Add etc/config/liberty/server.xml sample config with servlet-6.0,
  jdbc-4.3, transaction-1.2, T2 and T4 dataSource definitions
- Add .github/workflows/cleanup-old-runs.yaml (weekly, 30 day retention)

Author: Manvi-55

.github/workflows/cleanup-old-runs.yaml

@@ -0,0 +1,20 @@
+name: Cleanup old workflow runs
+
+on:
+  schedule:
+    - cron: '0 0 * * 0'  # Run weekly on Sunday at midnight UTC
+  workflow_dispatch:      # Allow manual triggering
+
+jobs:
+  cleanup:
+    runs-on: ubuntu-latest
+    permissions:
+      actions: write
+    steps:
+      - name: Delete old workflow runs
+        uses: Mattraks/delete-workflow-runs@v2
+        with:
+          token: ${{ github.token }}
+          repository: ${{ github.repository }}
+          retain_days: 30
+          keep_minimum_runs: 6

CODEOWNERS

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+# CODEOWNERS - Defines maintainers for this CICS sample
+# Docs: https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners
+# Last reviewed: 2026-08
+
+# For members of the team that maintains Java samples, see https://github.com/orgs/cicsdev/teams/cics-java-maintainers
+* @cicsdev/cics-java-maintainers