HOLD: Clarify payment Revert as removing an allocation

[maebeale]

What is the goal of this PR and why is this important?

• The payment "Revert" action only offsets an allocation and returns its amount to the payment's unallocated balance, but the bare "revert" label and a silently greyed-out row left admins guessing what it actually did.
• This reframes the action around what it does — removing an allocation — so the payments admin screens read clearly.

How did you approach the change?

• Renamed the action to Remove (trash icon) with a consequence-stating confirm that names the dollar amount returned, plus an explainer line under the Allocations heading.
• Added explicit Removed / Reversal badges so reverted originals and their offsetting rows are self-describing instead of just dimmed.
• Polished the payments index and detail views: results in a card with row hover, amber highlight on unallocated balances, an icon empty state, and sentence-case labels.

UI Testing Checklist

• Payments index: results render in a card, rows highlight on hover, unallocated amounts show amber, empty search shows the icon state.
• Payment detail: an active allocation shows a Remove button; confirming returns the amount to the unallocated balance.
• After removing, the original row shows a Removed badge and the offsetting row shows a Reversal badge with a negative amount.

Anything else to add?

• HOLD — not ready to merge yet; opening as draft for early visibility.
• View-only change; no controller, route, or revert behavior was modified. Rebased onto latest main (adopts the dollars_from_cents helper); Rubocop and Brakeman pass.

[maebeale]

🤖 From Claude: The two badges map to the revert mechanism: is_removed is the original allocation (reverted_id set), is_reversal is the auto-created negative offset row. Both hide the Remove action so a removal can't be removed again.