fix(hstore): preserve range-index ordering across partitions

[contrueCT]

Purpose of the PR

• close [Bug] HStore range-index scans don't guarantee global ordering or stable paging #3053

HStore range-index queries with a limit, offset, or page cursor require globally
ordered backend keys. The previous multi-partition path exposed partition
iteration order and an internal storage cursor, which could return the wrong
limited slice or skip entries on continuation.

This PR adds an explicit ordered range-scan path while leaving unbounded count,
joint-index, and cleanup scans on the existing path.

Main Changes

flowchart LR
    subgraph Store1["Store 1"]
        P1["Partition 1"] --> M1["Local K-way merge"]
        P2["Partition 2"] --> M1
    end
    subgraph Store2["Store 2"]
        P3["Partition 3"] --> M2["Local K-way merge"]
        P4["Partition 4"] --> M2
    end
    M1 --> G["Client global K-way merge"]
    M2 --> G
    G --> R["Ordered range-index results"]

Loading

• Preserve the next unread physical index key as the HugeGraph page cursor and
  preserve ordered index IDs through the following element lookup.
• Add ORDER_BY_KEY to the HStore scan protocol. Each Store merges its local
  leader-partition iterators, and the client globally merges one stream per
  Store instead of opening one stream per partition.
• Use fixed 64-entry pages, request later pages only when a Store's current page
  is exhausted, and bound concurrent first-page initialization to eight
  streams.
• Keep legacy scan ordering and cursor behavior unchanged for requests that do
  not explicitly select the ordered path. Client and Store nodes must be
  upgraded together before using ordered range scans.

Verifying these changes

• Trivial rework / code cleanup without any test coverage. (No Need)
• Already covered by existing tests, such as (please modify tests here).
• Need tests and can be verified as follows:
  • ClientSuiteTest: 13 tests passed.
  • ServerSuiteTest: 6 tests passed.
  • HstoreSessionsImplTest and HstoreTableTest: 8 tests passed.
  • GraphIndexTransactionTest, IdHolderTest, and QueryResultsTest: 4 tests passed.
  • git diff --check passed.

Does this PR potentially affect the following parts?

• Dependencies (add/update license info & regenerate_known_dependencies.sh)
• Modify configurations
• The public API
• Other affects: extends the HStore scan protocol; coordinated client and Store upgrades are required for the ordered path.
• Nope

Documentation Status

• Doc - TODO
• Doc - Done
• Doc - No Need

[imbajin]

Blocking: yes. Summary: The ordered range-index path has a multi-batch ordering defect and is unsafe during mixed-version Store upgrades. Evidence: static review of QueryList/QueryResults and NodeTxSessionProxy/store_stream_meta.proto at head b45fded.

[imbajin]

Blocking: yes. Summary: The ordered range-index path still has correctness, cursor, resource, and compatibility defects beyond the existing review coverage. Evidence: exact-head static review of QueryResults, ScanUtil, OrderedKvIterator, OrderedMultiPartitionIterator, and public scan contracts at b45fded.