Add evidence-safe qualitative research interview workflow

[philngt]

Summary

Add the unreleased research-interview skill planned for WOAFC Toolkit 0.7.0.

The workflow supports three bounded modes:

• design: create research briefs, participant criteria, consent scripts, question maps, interview guides, and
  analysis plans.
• conduct: run consent-gated interviews with real participants, one question per turn.
• synthesize: turn eligible transcripts or redacted notes into traceable themes, counter-evidence, decision
  implications, and research gaps.

Key changes

• Add separate participation and raw-transcript storage consent gates.
• Add an adaptive interview loop with dependency-aware question branches.
• Add shared-understanding checkpoints and explicit exit criteria.
• Support immediate skip, pause, correction, and withdrawal controls.
• Prevent simulated participants, suggested answers, and unsupported market or population claims.
• Default to pseudonymous IDs and redacted notes.
• Add a versioned study-bundle contract under:
  .toolkit/research-interviews/YYYYMMDD/<study-slug>/
• Add deterministic validation for consent state, artifact integrity, path containment, PII keys, withdrawn sessions,
  quote references, and raw-transcript authorization.
• Add fixtures, unit tests, routing cases, documentation, privacy guidance, and release-gate coverage.
• Update English, Vietnamese, and plugin README documentation.

Evidence behavior

Participant statements remain user-asserted. A transcript proves what a participant said, but does not prove that
the statement is true, representative, causal, or valid as market evidence.

Withdrawn sessions are excluded from synthesis. Raw transcripts may only exist when explicit raw-storage consent is
granted.

Validation

• Full release gate: 36 PASS, 0 FAIL
• Validator self-tests: 75 PASS
• Research-interview unit tests: 22 PASS
• Markdown link validation: PASS
• Expansion and routing contracts: PASS

Release status

research-interview remains Unreleased and is planned for 0.7.0. It is outside the v0.6.0 public-beta support
boundary.