fix: align CLI and HTML score color thresholds to prevent green/yellow inconsistency at 0.80-0.85 boundary

[decko]

Finding

File: src/raki/report/html_report.py:396 / src/raki/report/cli_summary.py:82

After PR #297, html_color_for_score() uses ZONE_THRESHOLDS where green >= 0.85, but cli_summary.color_for_score() (line 82) still uses the old green >= 0.80 / amber >= 0.60 constants. A score of 0.82 now renders as green in terminal output but yellow in the HTML report — a user-visible inconsistency between the two rendering paths.

The old HTML docstring explicitly stated "Matches the CLI color_for_score semantics", so this drift is likely unintentional.

Suggested Fix

Option A — share the threshold source:

• Import ZONE_THRESHOLDS in cli_summary.py and update color_for_score() to use ZONE_THRESHOLDS["score"]["green"] / ZONE_THRESHOLDS["score"]["amber"].

Option B — revert HTML threshold:

• If 0.85 was not an intentional product decision, set ZONE_THRESHOLDS["score"]["green"] = 0.80 to restore parity.

Option C — document the divergence:

• Add a code comment in both files explaining the intentional difference if it is a deliberate product choice.

Context

Found during review of PR #297 (ticket #287 — fix: severity distribution chart and zone coloring in score cards). Did not block the PR.

Acceptance criteria

• CLI color_for_score() and HTML html_color_for_score() use the same thresholds
• CLI imports thresholds from ZONE_THRESHOLDS in html_report.py (single source of truth)
• A score of 0.82 renders the same color in both CLI and HTML
• Existing color behavior for cost/duration metrics unchanged
• Tests verify CLI and HTML agree for boundary values (0.60, 0.80, 0.85)
• Towncrier fragment (changes/300.fix)

Plan

1. Extract ZONE_THRESHOLDS to a shared location (or import from html_report.py into cli_summary.py)
2. Update cli_summary.color_for_score() to use ZONE_THRESHOLDS["score"]["green"] and ZONE_THRESHOLDS["score"]["amber"]
3. Add tests comparing CLI and HTML output for boundary scores
4. Towncrier fragment

[decko]

Implemented in PR #350. Merged to main.