spb/metrika Public

- DTAReader: formats 117/118/119, both byte orders, all numeric storage
  types widened to Float64 with Stata missing codes (., .a-.z) mapped to
  the validity mask; str# and strL (GSO) load as strings; value labels
  read past but not yet applied; pre-117 files rejected with a clear
  message
- DTAWriter: format 118 (UTF-8, LSF), doubles + str# up to 2045 bytes,
  real map offsets so Stata/haven/pandas can seek
- ZQDataStore routes .dta through the native path for use and save
- ZQColumnData equality now ignores value slots at missing positions
  (undefined by contract, often NaN — synthesized == failed on NaN != NaN)
- Fixtures: haven-written 117 + 118 files; tests assert bit-identical
  numeric loads vs the CSV, lossless write/read roundtrip; haven
  cross-reads Metrika-written files (verified)
- 61 tests green

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

- MetrikaKit SPM package: ZQParser, ZQPlanner, ZQEngine, ZQData, ZQStats,
  ZQGPU, ZQGraphics, ZQPlugins (Swift 6, strict concurrency)
- ZQL parser: lexer, Pratt expressions, factor variables, prefix commands,
  column-cited errors with Levenshtein verb suggestions
- ZQData: DuckDB-backed load/save (parquet, csv, json, arrow)
- ZQStats: OLS via LAPACK QR, HC0-HC3 and cluster-robust SE, summarize,
  t/F distributions accurate in the far tails
- ZQGPU: Philox4x32-10 reference RNG, counter-addressable bootstrap
- ZQEngine: session actor with use/save/gen/replace/drop/keep/summarize/
  regress/count/list/graph/bootstrap/set seed/xtset/log
- SwiftUI app (xcodegen): console with history, variables sidebar,
  Swift Charts plots; sandboxed + hardened runtime entitlements
- Tests: 44 green (parser golden, R fixtures at 1e-10, Philox KAT,
  end-to-end engine); Tests/Fixtures/generate.R; Tests/Bench harness
- scripts: check_headers.sh + pre-commit hook, make_icns.sh, release.sh

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>