Rank source credibility and bias

Audit every source in this notebook for credibility, bias, and evidence quality.

For each source, score and explain:
1. Recency — how current is the underlying information? (use the source's own dates)
2. Provenance — primary, secondary, or tertiary? Who funded, published, or stands to benefit?
3. Evidence type — data, expert opinion, anecdote, or speculation? Which dominates?
4. Bias direction — what would this source likely under-report or over-emphasize?
5. Internal consistency — does the source contradict itself anywhere?

Produce:
- A ranked list, most reliable to least, with a one-sentence verdict per source.
- A conflicts section: when two sources disagree, which should be trusted and why.
- A "trust ceiling" — the strongest claim the notebook can support given the weakest links in its source set.

Be specific. "Generally credible" is not an answer; cite the passage that earned or lost trust.