Add non-filter VGI integration parity fixtures

[rustyconover]

Implements the remaining non-Filter-v2 C++ SDK and example-worker behavior exercised by the canonical VGI suite:

• split pagination, caching, batch indexes, partitions, TTL, and stale-token behavior
• multi-branch split and duplicate-name schema catalog fixtures
• multi-batch buffering finalize and stable input batch replay
• bearer-token identity/policy support and dedicated protected-worker harness lane
• distinct invalid-vs-expired split token errors
• tracked cleanup for every HTTP worker started by the harness

The split TTL metadata commit is isolated so it can be rebased cleanly with the concurrent generated capability work. This PR does not skip or weaken integration tests.

Validation on EC2 against exact VGI main 4c4811c:

• Clang 15 debug and release builds passed (VGI extension built with GCC 14)
• CTest: 7/7 passed
• all focused non-filter integration lanes passed
• complete canonical suite: 343 cases, with only 18 Filter-v2/capability-dependent residuals assigned to Implement Filter Encoding v2 parity #4/Add Filter v2 capability metadata #3
• dedicated protected HTTP bearer lane: 7/7 assertions passed