Split casehub-work-examples into core and full variants

[mdproctor]

Context

Part of epic #147 — Project Refinement. casehub-work-examples currently pulls the full optional module stack (including casehub-work-ledger, which transitively pulls casehub-ledger with its hash-chain infrastructure). A user who wants to run a basic WorkItem creation example gets the full audit/ledger stack as a side effect.

What

Split the examples module into two variants:

• casehub-work-examples-core — depends only on casehub-work (the core runtime); covers basic WorkItem CRUD, lifecycle transitions, CDI event observation
• casehub-work-examples-full — depends on all optional modules; covers ledger audit trails, spawn groups, AI skill matching, business-hours SLAs

Alternatively, structure as a single module with two runnable profiles (-Pcore, -Pfull) if Maven profiles are cleaner than two separate modules.

Acceptance Criteria

• A basic WorkItem creation example compiles and runs with no ledger dependency on the classpath
• The full example suite still works with all optional modules present
• CLAUDE.md (or the examples README) documents which variant to use for getting started vs full showcase
• Parent pom.xml updated accordingly

Notes

Current module: casehub-work-examples/. The ledger dependency chain: casehub-work-examples → casehub-work-ledger → io.casehub:casehub-ledger:0.2-SNAPSHOT. The examples README currently says "also requires quarkus-work" which is already stale — update it as part of this issue.