Improve main page character win-rate readability UI

[nodohan]

Motivation

• The character win-rate table on the main stats page was text-heavy and hard to scan at a glance.
• Make per-character performance easier to compare visually by surfacing rank, avatar, name, color-coded percentage, and a progress bar.

Description

• Updated views/pc/stats.ejs (drawCharFunc) to render each row with a rank badge, combined avatar + name block, and a compact winrateCell containing a color-coded percentage, a horizontal progress bar, and W/L chips.
• Added small logic to compute numeric rate and a tone class (rateNumber and rateToneClass with thresholds >=55 = high, >=48 = mid, else low) to drive color variants.
• Added styling in css/renewal.css scoped under the season stats (.season2025U #charRate) for badges, avatar layout, progress bar, and W/L chips to ensure consistent visual appearance.
• Existing sorting and search behaviors (toggleCharRate, toggleTotalMatches, searchChar) are preserved and work with the new row markup.

Testing

• Ran unit tests with npm test -- --runInBand, and all test suites passed (3 test suites, 14 tests passed).
• No automated visual tests were added; manual verification is recommended in a browser to confirm layout and responsive behavior.

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Codex Task