feat: show judge model name in HTML and CLI report headers

[decko]

Problem

The report JSON config contains llm_model and llm_provider (e.g., claude-sonnet-4-6 / vertex-anthropic), but neither the HTML report nor the CLI summary displays the judge model name.

The judge cost line shows Judge: 20 calls, 41,861 in / 11,558 out tokens — but not which model produced those scores. Users need to know which judge model was used, especially when comparing reports or evaluating calibration.

Current State

• config.llm_model and config.llm_provider are in the report JSON
• The CLI summary shows the Agent: model line (feat: distinguish agent model from judge model in reports #179) but no judge model line
• The HTML report shows Judge: with token counts but no model name
• The diff module compares judge configs and warns on mismatch, but the individual report view doesn't show the judge model at all

Proposed

Show judge model alongside the cost line:

CLI:

Judge: claude-sonnet-4-6 (vertex-anthropic) · 20 calls, 41,861 in / 11,558 out tokens

HTML: Add judge model to the header meta section, similar to the Agent model field from #179.

Files

• src/raki/report/cli_summary.py — add model name to judge cost line
• src/raki/report/html_report.py + templates/report.html.j2 — add judge model to header

Context

Found during v0.9.1 release verification — ran raki run --judge and couldn't tell which model scored the retrieval metrics without inspecting the JSON.

[decko]

Implemented in PR #209. Merged to main.