Expand pier critique: source filters, deterministic sampling, prompt redaction, richer viewer

- critique: add --source-agent/--source-model filters and --sample-seed
  for deterministic sampling before --limit
- critique: redact the rendered prompt from local logs and agent jsonl
  after each item, and exclude n_concurrent/limit from the resume key
- viewer api: filter critique items (agent, model, task, rating, tag,
  status, q), add a rating/tag heatmap, and report running/pending/
  missing item counts
- viewer ui: rebuild the critique run page with distribution charts,
  a resizable heatmap grid, and a shared chart toolbar; refactor job
  scaling/scatter/slope charts onto it
- docs/readme/examples: document the new flags and add a reference
  critique prompt
- tests: cover source filters, sample-seed, prompt redaction, resume key