Add Zensical documentation site with GitHub Pages

[tshan10]

Summary

Adds a full documentation site for DLM using [Zensical] with automated build and deployment to GitHub Pages.

What's included

Documentation site (docs/)

• Home — architecture overview, mermaid sequence diagram of the lock flow, key features, lock identity scoping, lifecycle
• Getting Started — Java 17 requirement, Maven dependency, build instructions, Testcontainers note, minimal end-to-end example
• Usage — builder parameter table, tabbed Aerospike/HBase init examples, all API overloads (tryAcquireLock, acquireLock, releaseLock), defaults table, error handling with switch on ErrorCode, complete lifecycle example, cleanup/destroy() section
• Locking Semantics — lock level key formats (DC#farmId#lockId, XDC#lockId), lock modes, full API reference tables, retry flowchart, error codes reference, exception propagation, thread safety notes
• Aerospike Backend — generation-based locking explanation, write policy details, set naming, retry behavior (guava-retrying), bin layout, initialization/cleanup
• HBase Backend — checkAndMutate locking, auto table creation with pre-split, TTL behavior, row key hash-prefix distribution, column layout, initialization/cleanup

CI/CD (.github/workflows/docs.yml)

• PR builds — pr-build-check job validates docs on every pull request (build only, no deploy)
• Deploy on push to main — builds and deploys to GitHub Pages via actions/deploy-pages
• Concurrency guard — pages-${{ github.ref }} group with cancel-in-progress: true to prevent racing deployments

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud