[NIDX-03 workstream] Replace the per-segment series index

Parent: #13990
Blocked by: #14007

Tracking parent — do not apply Backlog. Split this workstream just in time after NIDX-02 closes; downstream RED contracts must be based on the writer and reader seams actually merged on main.

End-state boundary

banyand/internal/storage.newSeriesIndex selects native sidx for Measure, Stream, and Trace. The completed workstream owns field-set-aware insert/update/delete, projection, exact/prefix/wildcard identity, field dictionaries, composed filters, deterministic series/index/time sort, index-mode Measure, statistics, snapshots, cache reset, and mixed-version external segment receive.

Required behavior

• Fixed product fixtures return independently declared series IDs, fields, timestamps, and versions.
• Native and pinned legacy nodes exchange raw segments in both directions without replay or conversion.
• Interrupted, invalid, and duplicate external transfers never become partially visible.
• Restart selects a complete committed generation.
• CRC32 fields remain layout-only and are never calculated or validated.

Just-in-time decomposition gate

After #14007 closes, use its measured boundaries and run reports to file ordered live-caller leaves. Each leaf adds one observable series capability and activates it through a named Measure/Stream/Trace path; no sidx core, codec, query helper, or receiver may merge solely for future use. Apply Backlog to one unblocked leaf only.

Completion criteria

All future leaves merge; the complete newSeriesIndex role and replication path are native; compatibility, crash, race, and product suites pass; and this workstream closes before NIDX-04 decomposition.

Lexical non-regression

Repository changes for every implementation leaf before the final removal may delete existing references but must add zero new case-insensitive bluge tokens and zero matching tracked paths. The gate includes imports and aliases, function/type/variable names, filenames and runtime names, strings, comments and messages, tests, fixture/provenance data, scripts, configuration, and generated assets. Compatibility evidence uses neutral legacy oracle or compatibility writer labels plus an immutable revision or content hash rather than adding a retired module name.

This lexical gate applies to repository changes, not to issue or archived-design prose that names the dependency in order to specify its removal.

Design

BDB-NIDX-SPEC-001 revision 0.2 — NIDX-03 behavior