feat: add oracle evidence safeguards

references/oracle/artifacts/.gitkeep

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+

references/oracle/artifacts/README.md

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+# External Oracle Artifacts
+
+This directory stores sanitized evidence artifacts referenced by `source_artifact`
+inside external oracle evidence packets.
+
+## Required Path Policy
+
+- Use repo-relative paths such as `references/oracle/artifacts/jhora_REDACTED_YEAR_moon_lahiri_v1.png`.
+- `source_artifact` must point to a file in `references/oracle/artifacts/` or to a documented external review location.
+- Mark the artifact kind as `external_oracle_artifact` in operator notes when possible.
+
+## Privacy Rules
+
+- 必须打码 any real person's full name, contact details, exact street address, hospital, account name, or other identifying text.
+- 不得提交私人 PDF 原件；only sanitized screenshots or typed stdout snippets belong here.
+- 不得提交完整出生报告 or full private reading transcripts.
+- 不得提交浏览器 scratch folders, screenshots containing account sessions, cookies, tokens, or desktop notifications.
+- Prefer synthetic fixtures, public figures, or heavily redacted screenshots.
+
+## Allowed Examples
+
+- Redacted JHora screenshot showing settings, Moon longitude, Dasha boundary, or Shadbala component table.
+- Redacted PyJHora stdout captured in a plain text file with command metadata.
+- Public-figure sample screenshot where source settings are visible and no private account data appears.
+
+## Not Allowed
+
+- Unredacted volunteer/client birth data.
+- `output_report.txt`, `results_extracted.md`, private PDFs, or full generated readings.
+- Local engine output from this repository pretending to be an external oracle.
+
+Evidence packets remain `draft` until their target values are filled, their
+artifact is reviewed, and their status is explicitly promoted to
+`external_verified`.