fix: SONA zero-vector bug, RVF wasm persistence, metadata safety (#704, #705, #706, #707) - #708

Summary

• SONA N-API applyMicroLora returns zero/delta instead of identity plus delta #706 — apply_micro_lora/apply_base_lora seeded their output buffer with zeros in napi.rs, napi_simple.rs, and wasm.rs, but the Rust LoRA forward pass has residual semantics (adds the delta into the buffer). Cold queries returned the zero vector; post-feedback queries returned only the delta instead of input+delta. Fixed by seeding the output buffer with a clone of the input in all three binding layers. Added 3 regression tests to npm/packages/sona/test/basic.test.js (verified they fail on the old code, pass on the fix, via a real build of the native addon).
• Browser docs advertise unshipped RVF APIs; WasmBackend has no persistence export/import #705 — WasmBackend had no byte-level persistence. The underlying rvf_store_export/rvf_store_open C-ABI functions already existed in crates/rvf/rvf-wasm — wired them into WasmBackend.exportBytes()/openBytes() and RvfDatabase.exportBytes()/openBytes(). Verified end-to-end against the real compiled .wasm binary (round-trips vectors through export → reopen).
• RVF SDK silently drops metadata; native metadata is not durable or returned #704 — NodeBackend.ingestBatch() silently dropped RvfIngestEntry.metadata instead of forwarding it to native, and query() filter serialization omitted the native parser's required valueType. A full field-name↔fieldId design for durable metadata is a larger follow-up (native metadata also doesn't survive close/reopen at the Rust level — separate issue), so this PR applies the issue's own suggested interim fix: ingest now throws MetadataNotSupported instead of silently losing data. Filter serialization now infers and includes valueType. 8 new tests.
• Node documentation advertises HybridSearch absent from ruvector@0.2.34 #707 — docs/api/NODEJS_API.md and docs/guides/ADVANCED_FEATURES.md advertised HybridSearch/FilteredSearch/MMRSearch/ConformalPredictor as Node exports; none are bound by crates/ruvector-node. Corrected with explicit "not yet shipped" notes.

Not included in this PR: README corrections for crates/rvf/README.md and npm/packages/rvf-wasm/README.md (both also describe the unshipped WasmRvfStore class). A local repo hook requires a screenshot-based visual design-grade for any README change that I can't complete in this environment (no browser/screenshot access) — will follow in a separate PR once that's sorted out, or feel free to fold the diff in yourself; it's a pure doc correction with no code risk.

Test plan

• cargo build -p ruvector-sona --features napi — compiles clean
• Built the real napi_simple addon (npm run build:debug in npm/packages/sona) and ran npm test — 14/14 pass including 3 new SONA N-API applyMicroLora returns zero/delta instead of identity plus delta #706 tests
• npx tsc --noEmit in npm/packages/rvf — clean
• Built the real rvf-wasm module path and ran new test-wasm-persistence.js against the actual shipped .wasm binary — 3/3 pass
• node tests/test-metadata-and-filters.js — 8/8 pass
• Full existing npm/packages/rvf/tests/* and npm/packages/sona/test/* suites — no regressions

Co-Authored-By: claude-flow ruv@ruv.net