Add Income Report extension

[santyr]

Adds the Income Report extension to the vetted registry.

• Repo: https://github.com/lightning-goats/incomereport_extension
• Release: v0.1.0
• What it does: Accounting-oriented income reporting over the core apipayments read model — daily / weekly / monthly / yearly income per wallet, fiat values recorded at payment time, bar + cumulative charts, and CSV export (both aggregated summary and a transaction-level ledger). User-scoped: each user sees only their own wallets.

Checklist

• ✅ No new dependencies — uses only what LNbits already ships (FastAPI, Quasar, the bundled Chart.js v4).
• ✅ Fully working — pure read model: no own tables/migrations, no background tasks, no invoice listener.
• ✅ id incomereport is unique in the registry.
• ✅ Icon is a PNG served from main; the hash matches the tagged source archive.