Priority report: fix badge colors to match tier definitions

[Brandon-Haney]

Fixes #175

Problem

On the Priority Report (and the storage breakdown, file table, and eviction simulator), the per-item score badges were colored with outdated thresholds — >= 70 for green/high and >= 40 for orange/medium. The Priority Distribution legend and the backend tier counts use 90-100 high, 70-89 medium, 0-69 low. As a result the badge color contradicted the legend: a score of 85 or 70 showed green (when the legend marks them medium), and a 60 showed orange (when the legend marks it low/eviction).

Fix

Align the badge color thresholds in the four templates with the canonical tier boundaries already used by the backend (cache_service.py):

• >= 90 -> high (green)
• >= 70 -> medium (orange)
• < 70 -> low (red)

This makes the list badges match the Priority Distribution cards, the footer summary badges, and the actual eviction behavior.

Test steps

1. Cache a set of items with a spread of priority scores (or use --show-priorities).
2. Open the web UI -> Cache -> Priority Report.
3. Confirm the score badge colors now match the Priority Distribution legend:
   • 90-100 renders green (High)
   • 70-89 renders orange (Medium)
   • 0-69 renders red (Low)
4. Spot-check the Storage breakdown, the cache file table, and the eviction simulator preview — badge colors are consistent everywhere.