Chore: spotlight zone upgrade

[scode2277]

What does this PR change?

Spotlight Zone: badge icons and legend rework

• Moved the legend above the contributor list as a collapsible panel, and added a Tiers section explaining each rank.
• Sort contributors by earned badges first, then activity status, then recency, using the most recent activity date rather than the first found.
• Renamed the medal tiers to Bronze / Silver / Gold (25 was "Diamond"), reviewers to Trusted / Senior, issue rungs to Reporter / Observer / Investigator, and promoted Lead to legendary.
• Activity badges show "Status" on the tooltip instead of a rarity.
• Fixed badge dates shifting a day by timezone, gave badge cards a proper role="img" label, and removed the unused intersection observer hook.
• Rebuilt badge icons on shared SVG primitives, with per-render unique gradient ids so badges no longer collide when the same one appears on several cards.

have a look at it here -> https://chore-spotlight-zone.frameworks-573.pages.dev/contribute/spotlight-zone

Type of change

• New content
• Edit to existing content
• Outline / structure change
• Typo or formatting fix
• Tooling / config

If applicable

• Editing existing content: tagged the current contributors from the attribution list
• Framework has a steward: asked them to review
• Outline change: updated vocs.config.ts with the dev: true parameter
• Want community feedback: shared this PR in our Discord

Stuck on anything? Just write it here and we're happy to help.

[frameworks-volunteer]

Model: x-ai/grok-4.6 Reasoning: medium Provider: openrouter

Security: no secrets, no eval/innerHTML, no user-controlled markup. Badge SVGs stay in JSX. badgeIconUid strips ids to [A-Za-z0-9_-], so gradient/mask ids cannot collide or inject. Badge labels/descriptions come from BADGE_CONFIG, not raw JSON names in markup.

QA: matches the PR body. UTC timeZone on dates, unique per-render icon ids, role="img" + aria-label, legend moved above the list, sort by earned badges then activity then recency, medal/reviewer/issue rename, Lead at legendary. CI green (5/5).

Nit (non-blocking): HIDDEN_BADGES is empty, but Contributors.tsx still comments that Dormant is never drawn. Either hide it in the set or drop the comment.

Approve.