feat(jsonhtml): add prepared exports and typed diagnostics

[ThorFuchs]

Adds immutable JSONHTML prepared exports for exact JSON, UTF-8 text, Markdown and expanded script-free HTML; styled RTF is opt-in and Apple PDF requires explicit awaited MainActor preparation. Transfer returns only existing selected artifacts, imports strict native JSON only, and preserves exact numbers, scalar keys and insertion order under finite cumulative budgets.

Typed caller diagnostics attach to exact value paths or explicitly identified existing parents. Coherent JSONDocument input supplies value/parent UTF-8 spans without archiving original source bytes or executing schema validation. Shared writer defaults and initializer function types remain compatible. Selected item-provider filenames follow the actual advertised preference, including PDF-only selections.

PR #21 is merged. This PR now targets main at d463d04. Reviewed head a0a73b0 transplants only the child commits onto the identical merged parent tree and adds nine documentation/ledger corrections. Runtime code, tests, assets, harnesses, limits and dependencies are unchanged from the qualified parent, apart from one Swift documentation comment. Historical acceptance records are retained; all 84 implementation rows are mapped to actual evidence. No independent reviewer or self-approval is claimed; live required checks and review threads remain mandatory.

Qualification: native 270 functions/173 parameters, ASAN 270/173, TSAN 10, all 49 cap probes, 38 focused export functions, 65 public consumer outcomes/eight artifacts, 46 browser cases with zero skips, and five DocC catalogues covering 771/771 authored declarations and 13 executed README fences. Linux/Node portable root discovery is 256/173; WasmKit remains limited to its 14-function public consumer/probe scope. Pinned independent corpus policies and operational-error distinctions remain unchanged. The final-head hosted native/safety/docs and both Linux architecture lanes bind this documentation successor; the local DocC lane has also passed on its exact source bytes.

The 65-outcome consumer executed on Mac, physical iPhone and both simulators. Three actual Mac JSON/Markdown/generic-text drag destinations passed exact comparisons. Physical iPhone and iPad simulator Save to Files/reopen confirmed the unedited A4.pdf name, seven pages and final sentinel; the simulator's saved bytes exactly match preparation. Native Safari diagnostic target/parent navigation passed in interactive and static formatted output. The maintainer confirmed four interactive diagnostic VoiceOver checks; VoiceOver was restored off. Human speech/receiver observations remain distinct from automated API and byte inspections. Physical iPad retains the approved simulator policy; TextEdit rich-save Unicode normalization remains a documented recipient limitation.

Eighteen release-native and 54 three-engine browser observations cover six representative wide/deep/Unicode/annotated workloads. Actual DOM bounds, controls, search and offline policy passed. These are busy-host representative measurements, not idle A/B, maximum-workload, RSS or browser/SDK instruction guarantees. The 10% review trigger and prior streaming/schema dispositions are unchanged. Source/evidence archives and reproduction receipts remain materialized with manifests; private logs/device records are outside Git. No tag, release publication or protection change is included.