Add CI coverage for HyperCore 9.6 / 9.7 / 9.8; fix existing 9.5 coverage gap

[ddemlow]

Requirement

The collection's documented "tested against" HyperCore version list currently stops at 9.5.5.219383.
We need:

1. Confirmed, working CI coverage for 9.6 (priority), then 9.7, then 9.8.
2. 9.8 is an early-release build — please test it on a schedule/trigger that keeps it isolated from
   the main nightly signal (early-release builds are more likely to have transient issues unrelated
   to the collection itself; we don't want that noise obscuring real regressions on the stable
   versions). How you isolate it — separate workflow, workflow_dispatch-only, looser cron,
   whatever fits your existing setup — is your call.
3. Documentation (README, docs site) updated to reflect whatever is actually covered once done.

Also found while scoping this

9.5 is currently documented as tested but not actually covered by CI. Worth confirming and
fixing as part of this same pass, since it's the same category of gap.

Open items on our side

• Exact build strings for 9.6 / 9.7 / 9.8 (@ddemlow to confirm once test hosts are available).
• Flag if anything needs provisioning that only Dave/Scale can grant (network access, identity
  provider app registration, etc.) and we'll get it sorted.

Reference (not a spec — just what we found reading the repo, in case it saves you a discovery pass)

• README.md / docs/rst/index.rst carry the "tested against" version list (kept in sync manually
  today).
• tests/integration/integration_config.yml.j2 already has a fully-configured block for 9.5
  (10.5.11.206), but none of .github/workflows/integ-test.yml's matrix jobs reference it — that's
  the specific 9.5 gap above.
• DEVELOPMENT.md's "Adding new CI test cluster" section describes the current process for adding a
  new version's test host, if useful — treat it as a starting point, not a constraint, if your own
  infra now works differently.