docs(billing): add Linkrunner Wallet and how to pay an invoice

[tashviks]

Billing had a single page and it never said how to actually pay an invoice. The supported payment methods list also predated Cashfree and bank transfer.

What this adds

Billing now has two pages, as requested:

• Billing Overview — the existing page, with Invoices & Payments rewritten. The methods list gains Bank transfer and Linkrunner Wallet (and Cashfree, which was missing), followed by three short sections: pay by bank transfer, pay by card/UPI/netbanking, pay from your wallet.
• Linkrunner Wallet — new. Adding funds, how invoices settle from the balance, available vs locked balance, withdrawals, and a troubleshooting accordion.

Accuracy

Every claim was checked against the shipped code rather than the PR descriptions, which caught two things:

• Bank transfer is INR-only, and both pages say so. Worth noting explicitly because there was an in-flight change to open it to every currency; that work has been dropped, so the INR-only wording is correct for what customers actually have today.
• No percentages anywhere. Free-install bonus rates, the gateway charge and the withdrawal processing fee are all configured per account. Quoting today's numbers would make the page wrong for most readers and wrong for everyone the day an operator changes them, so the pages say the figure is shown before you confirm.

Also deliberate: an invoice settles in full or not at all, which is why the bank-transfer steps insist on the exact amount. That is the single most likely way a customer wastes a trip to their bank, so it appears in the steps, in the FAQ, and in the wallet page's settlement section.

Customer-facing only

No console, approval-queue, or reconciliation detail. A customer submits a UTR and the invoice is marked paid once we match it; how that match happens is not their problem.

Screenshots

Both dialogs are now shown, captured from dashboard.linkrunner.io:

• Pay Now on the overview page, under "Pay by bank transfer".
• Add funds on the wallet page, under how to pay.

The invoice ID is blurred. Nothing else on those dialogs needed redacting: the account details shown are Linkrunner's own published deposit account, which is precisely what the page is telling customers to pay into. Each is cropped to the dialog and matted on the app's background token so the padding reads clean instead of showing the dimmed page behind it.

One thing to know about the add-funds shot: it is an account with no paid invoices yet, so the dialog offers only Custom amount rather than the 3/6/12 month suggestions the page describes. That is genuine behaviour for a new account, not a bug, but it is why the image sits under how to pay rather than under choosing an amount. If you would rather it showed the suggestion ladder, that needs a wallet-enabled account with billing history and I will recapture.

Checks

• docs.json is valid JSON and the Billing group lists both pages; rebased onto latest main, where two other PRs had touched docs.json, so their nav entries are preserved and my change there is still a single line.
• No em-dashes, per the writing rules.
• Both nav paths resolve to real files.
• Not previewed with mintlify dev.

🤖 Generated with Claude Code

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