P0 residual: reference servers fail V-1 (CF driver cannot surface 64-bit integers) -- blocked on workerd#4195

[ssilvius]

Residual scope after PR #19 (reopened by the spec owner -- the original text pre-commits against closing on a lossy implementation)

What landed (v0.2, PR #19): S6.1 "Response value encoding" emission MUSTs keyed on the STORED value; conformance cases V-1..V-4 writing values as SQL literal text so the driver path is what gets tested; fixture columns with affinity rationale.

What remains open -- the driver-layer half: both Cloudflare reference servers provably FAIL V-1 today, and cannot be fixed at the encoding layer:

• D1: the API does not surface bigints ("BigInts are not currently supported in the API yet").
• Durable Objects: SqlStorageValue is ArrayBuffer | string | number | null; the storage docs state a large int64 "may be less precise than your original number" on retrieval.
• Both tracked upstream at D1 Javascript API: Support BigInt cloudflare/workerd#4195. Both servers carry KNOWN NON-CONFORMANCE annotations in code and README with the workaround (SELECT CAST(col AS TEXT)).

This issue closes when either workerd#4195 (or an equivalent API) ships and both reference servers pass V-1 with real 64-bit values, or a deliberate spec-owner ruling downgrades the reference servers' V-1 status permanently (not the default -- the reference servers exist to demonstrate conformance).

Guard unchanged from the original: do not close this with an implementation that still loses the value.