docs: add GitHub-only budget policy and reporting page

BUDGET.md

@@ -0,0 +1,78 @@
+# QuantCLI budget
+
+QuantCLI is a small open-source project that maintains three CLIs for exporting
+your own quantified-self data. This page is the canonical record of project
+funding and operating costs.
+
+## Operating envelope
+
+The operating spend ceiling is **$300 per month**. This is a policy limit, not
+actual expenditure, a fundraising target, or a promise to spend.
+
+Public approval record: [board review and publication PR](https://github.com/quantcli/common/pull/39). Increasing the
+ceiling or taking on a recurring cost requires prior Executive Director and
+board approval. Contributions do not automatically authorize new spending.
+
+## Funding and independence
+
+Our funding platform is [GitHub Sponsors](https://github.com/sponsors/quantcli).
+Public acknowledgements belong in [SPONSORS.md](SPONSORS.md).
+
+Sponsors support continued operation. They do not buy governance influence,
+roadmap input or priority, contract concessions, exclusive access, private
+support, a support SLA, or product endorsement. These terms apply equally to
+individuals, companies, and competing tool vendors. There are no private terms
+or side agreements. Technical decisions do not depend on sponsorship.
+
+## What operating costs cover
+
+| Category | Evidence required for actual spending |
+| --- | --- |
+| Infrastructure and hosting | Provider invoice or receipt for project services |
+| Agent runtime | Project-attributable usage and billing records |
+| Domains and DNS | Registration or renewal receipt |
+| CI and build services | Invoice for project charges |
+| Platform and payment fees | Actual fee entries in primary platform records |
+
+These categories describe costs that may be reported, not spending allocations
+or new commitments. Founder-paid costs, reimbursements, and in-kind credits are
+identified separately when evidenced. No fee percentage or reserve balance is
+assumed.
+
+## Monthly snapshots
+
+The first report will be prepared in December 2026 following the November 9
+GitHub Sponsors launch. Its reporting period and source cut-off will be stated
+explicitly. The first reporting period is November 9–30, 2026, in UTC.
+
+No verified snapshot has been published yet. Missing records do not establish
+zero receipts, zero expenses, or a zero balance.
+
+Each report will link public primary records for opening and closing balances,
+GitHub Sponsors receipts, refunds, actual fees, other project payments, and the
+reconciliation between them. Platform payouts will be identified as transfers
+when appropriate, without counting them twice as income. Original currencies
+and any evidenced conversions will be stated.
+
+Reports will compare actual spend with the approved envelope, explain anomalies,
+and link releases or other shipped artifacts for the period. Cost per shipped
+artifact will use a stated counting rule and sourced totals. The first report
+will be labelled as the first reporting period, without an invented prior-month
+comparison.
+
+Private sponsor identities and payment details will not be published. Public
+source records must retain sufficient evidence to reproduce the reported totals.
+Figures without an accessible primary source will be held until evidence is
+available.
+
+## Review and corrections
+
+Sustainability prepares updates through pull requests. The Executive Director
+reviews the text, source records, and figures before the board approval and merge
+step. A monthly update does not authorize a change to sponsor rights or future
+spending.
+
+Report an error through an issue in
+[quantcli/common](https://github.com/quantcli/common/issues), with `budget` in the
+title and a link to the affected public source. Do not put private payment
+records or sponsor identities in a public issue. File history is the audit trail.