Fix job history for constructed inventory hosts

[fernandorocagonzalez]

Summary

When looking at a host or group inside a constructed inventory, the job history (job_host_summaries endpoint) was coming back empty. This happened because the API was querying the wrong foreign key on JobHostSummary: it used the host FK (which points to the source inventory host) instead of constructed_host (which points to the constructed inventory host). The serializer already handled this correctly for the recent_jobs field, but the full list endpoint did not.

On top of that, when an inventory source syncs with overwrite and a host temporarily disappears from the source, the host object gets deleted and recreated with a new PK. The old JobHostSummary records lose their host link (SET_NULL), so even after the host comes back, the job history is gone. This adds a relink step after each inventory sync that reconnects those orphaned records by matching on host_name, scoped to the same inventory so it wont accidentally link summaries from a different inventory that happens to have a host with the same name.

Changes:

• HostJobHostSummariesList and GroupJobHostSummariesList now use constructed_host_summaries for constructed inventory hosts/groups
• New Group.constructed_host_summaries property (Host already had one)
• New _relink_orphaned_job_host_summaries method in inventory_import, called after each sync
• 12 new tests covering the API fix, the relink logic, constructed inventories, and cross-inventory isolation

Test plan

• Existing tests pass (48 inventory import + 8 host summary = 56 total, 0 regressions)
• New test: constructed host job summaries returned via API
• New test: regular (non-constructed) host summaries still work
• New test: no false positives (summaries from source inventory dont leak to constructed)
• New test: constructed group summaries returned via API
• New test: orphaned summaries re-linked after host is deleted and recreated
• New test: summaries not re-linked when host PK is preserved (no orphan)
• New test: constructed inventory orphaned summaries re-linked via constructed_host FK
• New test: re-link does NOT cross inventories (inventory A sync wont steal inventory B orphans)