[Airdrop] Streak card: show current boost tier, fix button color, tidy boost table

[realproject7]

Parent: #877

Issues

1. Current boost tier not shown in header

The header shows "⚡ 0 Days Streak" but doesn't display the user's current boost tier. When the user has a boost, it should be prominent — e.g., "⚡ 12 Days Streak · +10% Boost"

If no boost yet (< 7 days), show "No boost yet" or "Next: 7 days → +5%"

2. Check In button text color should be white

The button has brown background (bg-accent) but the text blends in. Set text color to white explicitly.

3. Boost tiers table is untidy and wordy

Current layout is plain text rows with a long explanation paragraph. Needs visual polish:

Fix:

• Use a clean 3-column layout: streak threshold | boost % | status indicator
• Current tier row: highlighted background with "← active" badge
• Unlocked tiers: subtle checkmark
• Locked tiers: greyed out
• Remove the wordy paragraph, replace with a single concise line: "Miss a day → drop one tier"
• Add visual separator between table and explanation

Example:

┌────────────────────────────────────┐
│  BOOST TIERS                       │
│                                    │
│  7+ days    +5%     ✓              │
│  14+ days   +10%    ← active      │  ← highlighted row
│  30+ days   +20%    🔒             │
│  50+ days   +30%    🔒             │
│  100+ days  +50%    🔒             │
│                                    │
│  Miss a day → drop one tier        │
└────────────────────────────────────┘

Files

• src/components/airdrop/StreakCard.tsx

Acceptance Criteria

• Header shows current boost tier (e.g., "+10% Boost") or "Next: 7 days → +5%"
• Check In button text is white
• Boost tiers table: clean 3-column layout, highlighted current tier
• Locked tiers show 🔒, unlocked show ✓
• Explanation condensed to one line