v0.3.0 — Historical polardata rebuilt from poll sources

Recreate historical polardata from public poll-level sources, without the local vault or frozen aggregate inputs.

• Reconstruct all 848 respondent-field targets across 21 historical polls.
• Export the complete 6,084-row, 364-column historical schema and 129-row attitude-index catalog under output/polardata/.
• Keep canonical people unique, preserve the 217 duplicated Primaries people in the historical wide export, and publish derived measures separately.
• Preserve historical coding choices, source versions, sample stages and intermediate precision. Detailed poll-specific findings and required instrument checks are recorded in docs/poll-issues.md for later corrections.
• Explain 288 generalized-variance differences in 24 groups through exact source-matrix checks and numerical diagnostics. Export row numbers are regenerated; every other value and missingness comparison passes.
• Preserve all 15 existing core, linkage and partial UK Health outputs byte-for-byte. Downstream repositories retain their existing input pins.

The release archive contains the source inputs, identity/order ledgers, code and outputs. make check rebuilds and validates the pipeline. Third-party materials retain their existing rights; this release does not grant new rights to them.

Validation: local and independent isolated make check each passed 2,141 assertions with zero failures, warnings, skips or lint findings. Hosted CI passed for the reviewed candidate and publication commit. A clean source-archive rebuild, with the vault, benchmarks and prior outputs absent, reproduced all seven aggregate products byte-for-byte; the restored benchmark comparison also passed.

Publication commit: a408904b20d65c2b8a1ccd556cdb8c9dff100aa9. Reviewed candidate: 4fa913adce4a567c61e0291f6496406cff97fdde (identical tree).