fix(ceremony): read JSON fields with the whitespace beside structure removed

[xgreenx]

An alternative to #36 for the same defect: GitHub pretty-prints /user for the media type the profile pins (accept: application/vnd.github+json is the trigger, checked live; without it the JSON is compact), so readers matching "login":" and "id": byte for byte refuse every real identity read.

The approach

Normalize once, then keep every reader's exact template, the way normalizeHeaderBytes already serves the request head. CeremonyFields.normalizeJsonBytes removes a run of JSON whitespace (0x20 0x09 0x0a 0x0d) only where it touches a structural byte, : , { } [ ], which is exactly where JSON puts insignificant whitespace. A run between two tokens stays: 123 4 does not read as 1234, and a space after digits is still the byte the terminator check judges.

• tryJsonString and tryJsonInteger normalize their range first; the cross-range duplicate counts in the base normalize the concatenation.
• Bearer framing: the revealed range ending where the commitment starts is the anchor and its normalized bytes must end with "access_token":"; the prefix may appear at most once across everything revealed; a prefix split across ranges is refused, since no single range carries it.
• Stateless by design: a reader with a notion of "inside a string" is one a prover desynchronises by cutting a revealed range mid-value. No needle can be manufactured by removing whitespace, since one needs unescaped quotes, and nothing read carries whitespace beside a structural byte inside its value.

Compared with #36: the same acceptance and the same refusals, one normalization instead of a tolerant matcher at each reader, the templates unchanged, and 20 fewer lines in the verifier.

Tests

458 pass, up from 450. CeremonyFields.t.sol: pretty-printed members read, a duplicate in another spelling is still a duplicate, only the four JSON bytes are removed (a vertical tab is not), 123 } reads and 123 4 is refused at the space. CeremonyAttestation.t.sol: a bearer framed behind whitespace, one byte off refused, a second compact prefix ambiguous, a prefix split across ranges refused. GitHubPlatformVerifier.t.sol: the response GitHub actually serves reads as 583231 / octocat; a second login spelled with spaces is FieldNotUnique; test_rejectsAnIdWithoutAStructuralTerminator now uses 583231 4, since 583231 } is JSON.

Sizes stay well under the 24,576 limit, measured on this branch: GitHubPlatformVerifier 16,636, XPlatformVerifier 15,728, GoogleJwtRoots 14,725 runtime bytes.

The prover side reveals the whitespace inside the member at its offsets: libid-org/libid-rs follows in its own PR. Specification wording: libid-org/libID#32 covers the tolerance; if this shape is preferred, its "MUST NOT reconstruct by dropping whitespace" sentence should say "across ranges", since dropping it within one range is what this does.

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