feat: logosdb 0.8.0 — sync, stats, compact, doctor, snapshots, stress suite

[jose-compu]

Summary

Ships logosdb 0.8.0: durability and ops (sync, snapshot/restore, stats, compact), CLI doctor/upgrade, opt-in stress tests (including concurrent API use), search paths taking the DB mutex for safe sharing of one handle across threads, and version / packaging alignment (CMake, C header, Python, Node vendored core, MCP, n8n, npm workspaces + CHANGELOG).

Closes #81
Closes #82
Closes #83
Closes #88

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Changes

• Feature: logosdb_sync / CLI snapshot & restore (snapshot.json v1)
• Feature: logosdb_stats / CLI stats (+ Python DB.stats())
• Feature: logosdb_compact / CLI compact (+ Python compact)
• Feature: CLI doctor / upgrade (vectors v2, probes)
• Feature: Opt-in doctest suite stress (default ctest excludes via --test-suite-exclude=stress)
• Fix: Serialize logosdb_search / logosdb_search_ts_range under db->mu vs concurrent writes
• Chore: npm 0.8.0 (logosdb, logosdb-mcp-server, n8n-nodes-logosdb), root workspace includes n8n, remove redundant n8n/package-lock.json
• Refactor: Remove dead start_id / stale WAL comment in put_batch (clean Node build warning)

Type of Change

• Bug fix (non-breaking change which fixes an issue) — search mutex vs concurrent mutators
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update — README threading note, bench version line, CONTRIBUTING / MCP README / CHANGELOG
• Performance improvement — search now contends on mu with writes (slight contention vs prior lock-free search)
• Refactoring (no functional changes)

Testing

• Unit tests added/updated — test_doctest.cpp + test_stress.cpp
• Integration tests pass — npm run npm:verify (vendor-core, logosdb native tests, MCP tests + smoke)
• Manual testing performed — ctest --output-on-failure, ./logosdb-test --test-suite-exclude=stress, ./logosdb-test --test-suite=stress, Release CMake build

Describe the tests you ran:

• cmake -S . -B build -DCMAKE_BUILD_TYPE=Release -DLOGOSDB_BUILD_TESTS=ON && cmake --build build && cd build && ctest --output-on-failure -V
• ./logosdb-test --test-suite-exclude=stress and ./logosdb-test --test-suite=stress
• npm run npm:verify from repo root

Checklist

• Code compiles without warnings on GCC and Clang — Node put_batch unused-var warning addressed
• Tests pass (ctest --output-on-failure, pytest) — CMake/doctest + npm verify; run pytest if you touch Python further
• Benchmarks run if performance-related
• CHANGELOG updated for user-facing changes
• Documentation updated (README, headers, guides) — README minimal threading + bench version; CONTRIBUTING / MCP README
• PR title follows conventional commit style (feat:, fix:, docs:, etc.)

Additional Notes

• Threading: Search now shares the same mutex as writes so stress tests and multi-threaded clients do not race the HNSW index / metadata; concurrent searches serialize with each other and with writes.
• npm: Use root npm install so n8n resolves workspace logosdb; publish logosdb → logosdb-mcp-server → n8n-nodes-logosdb after registry has native 0.8.0.
• Vendored core: Run npm run vendor-core -w logosdb (or npm:verify) so nodejs/deps/core stays in sync with src/ / include/.