Fix DOM parse() lifetime on the Vector backend (B17)

[devcrocod]

Summary

Audit finding B17: on the Vector backend, parse() returned lazy JsonObject/JsonArray views over the parser's single reused Tape + stringBuffer. A subsequent parse()/iterate() on the same parser overwrote those buffers in place, silently corrupting previously returned DOM values (reproduced: ClassCastException, stale size) — while the JsonValue KDoc promises "Immutable and safe to share across threads" and the parser KDoc recommends reuse. JNI/Native already materialized eagerly, so the contract also diverged across backends.

Changes

• Eager materialization: TapeValueMaterializer moves commonMain → jvmMain and recursively builds list-backed JsonObject(entries)/JsonArray(elements) — the same shapes JNI/Native produce. TapeBuilder.createJsonValue() unchanged.
• Dual-mode removal: JsonObject/JsonArray lose the tape-view representation and become plain list wrappers; public surface (size, get, keys, contains, iterator) unchanged. Net −38 lines.
• Tape.kt moves commonMain → jvmAndAndroidMain (its only users are TapeBuilder/TapeValueMaterializer in jvmMain and NumberParser in jvmAndAndroidMain).
• KDoc: both parse() overloads now state the guarantee — the returned tree is fully materialized and independent of the parser, valid after subsequent parse/iterate/close. On-Demand (iterate()) keeps its documented borrow semantics.
• Regression tests (commonTest, run on every backend): deep re-read of an old result after reparse, DOM survival across iterate() (string root deliberately clobbers the shared stringBuffer), DOM survival after close().

Testing

• Red phase confirmed: the new reuse/iterate tests failed on Vector (NPE / assertion) and passed on JNI before the fix.
• Green: jvmTest 536/536, jvmTest128 536/536, jvmTestJni, macosArm64Test, testAndroidHostTest, :simdjson-kotlin-serialization:allTests — all passing locally; Linux/iOS native covered by CI.

Trade-off: Vector DOM parse now allocates the object graph (the cost JNI/Native already pay; Jackson-tree equivalent). The zero-alloc "read a few fields" use case remains served by iterate().

[Copilot]

Pull request overview

This PR fixes a correctness/lifetime issue in the Vector (pure Kotlin) backend where parse() previously returned lazy DOM views over a parser-reused tape + string buffer, causing previously returned JsonObject/JsonArray values to become silently corrupted after subsequent parse()/iterate() calls. The change aligns Vector DOM behavior with JNI/Native by eagerly materializing an independent object graph and updates tests/KDoc to enforce the intended immutability and parser-reuse contract.

Changes:

• Eagerly materialize Vector DOM results into list-backed JsonObject/JsonArray structures so results survive parser reuse, iterate(), and close().
• Remove the tape-view representation from JsonObject/JsonArray (DOM now consistently list-backed across backends).
• Add cross-backend regression tests covering parser reuse, DOM survival across iterate(), and DOM survival after close(); update parse() KDoc to state the guarantee.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
simdjson-kotlin/src/jvmMain/kotlin/io/github/devcrocod/simdjson/TapeValueMaterializer.kt	New JVM Vector materializer that recursively builds list-backed DOM nodes from the tape + string buffer.
simdjson-kotlin/src/jvmAndAndroidMain/kotlin/io/github/devcrocod/simdjson/Tape.kt	Moves Tape to the JVM/Android source set to match actual usage and support the new JVM materialization flow.
simdjson-kotlin/src/commonTest/kotlin/io/github/devcrocod/simdjson/DomParsingTest.kt	Adds/expands regression tests to ensure DOM results remain valid across reuse, iterate, and close.
simdjson-kotlin/src/commonMain/kotlin/io/github/devcrocod/simdjson/TapeValueMaterializer.kt	Removes common materializer that previously produced tape-backed JsonObject/JsonArray views.
simdjson-kotlin/src/commonMain/kotlin/io/github/devcrocod/simdjson/SimdJsonParser.kt	Updates parse() KDoc to explicitly guarantee returned DOM independence from the parser lifecycle.
simdjson-kotlin/src/commonMain/kotlin/io/github/devcrocod/simdjson/JsonValue.kt	Simplifies JsonObject/JsonArray to plain list wrappers (no tape-view mode).

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