dp-data v0.4.0

This release rebuilds the corrected historical aggregates from public poll-level sources and preserves the available survey phases in typed Parquet.

Corrections distinguish absent questionnaires from blank answers within observed forms, retain positive attendance evidence, and treat unknown discussion groups as missing membership. The release includes the approved New Haven, BTP National and UK–EU fixes, a shared questionnaire-presence reconciliation, and both authored Zeguo township-image definitions with distinct names.

Original Bulgaria Crime survey files and coding drafts, Australia attendance evidence, Europolis's master questionnaire, and New Haven recruitment identifiers are retained in their poll folders with provenance and readable document companions.

Validation: full local tests and lint passed; independent review verified the corrections and source preservation; full CI passed on release commit 0970d70. The issue register records the remaining source and instrument limitations. Bulgaria 2007 respondent data are still unavailable, so this release does not claim a completed respondent-level audit of that poll. Weight use remains undecided.