Rename .musdc-inline CSS class to token-agnostic name

[tomazzi14]

Context

Follow-up to #14 (renaming .musdc-pill → .token-pill). The companion class .musdc-inline was missed in that pass — it still ships as .musdc-inline in frontend/app/globals.css and 2 consumers, even though the user-facing text was relabeled mUSDC → SOL back in GHB-81.

Acceptance criteria

• Rename .musdc-inline → .token-inline (or similar token-agnostic name) in frontend/app/globals.css
• Update all consumers:
  • frontend/components/CreateBountyForm.tsx
  • frontend/components/BountyEditMenu.tsx
• Visual output unchanged — span still renders SOL everywhere
• No new TypeScript or ESLint errors

Why now

Same rationale as #14: future tickets may add USDC/SPL token support, the class name should already be neutral so we don't have to do a third rename pass when the inline label becomes dynamic.

Size

Small — same shape as #14 (small CSS + 2 consumer file edits).