The ported engine wins every conflict: main's post-fork patches to the
hand-rolled Scanner and TokenEventParser land on deleted files and are
dropped; their behaviors are carried by the port and guarded by the
whole-suite conformance gate (402/402 passing).
Merge adaptations, all gates green (style, namespacing, forbidden
patterns, changelog, roadmap, swiftformat, swiftlint strict, build,
full test suite, whole-suite conformance sweep):
- PureYAMLJSON representability rules move onto the Check algebra,
replacing the retired legacy Rule type.
- The permissive tag-handle pre-pass is removed; the port rejects an
undefined handle at parse time (suite case QLJ7) and the validation
report carries it as a parse diagnostic.
- EventStreamComposer's nested types split one-per-file per the
namespacing gate.
- Tests pinned to old-engine behavior were re-verified against the
reference and updated: libyaml rejects an explicit-key continuation
ending at a value colon, and suite case QB6E requires rejecting a
quoted continuation at column 0.
- CHANGELOG unreleased entries from both lines are preserved in two
groups with a provenance note.
Closes#1, closes#3
A plain scalar continuation that ends at a `:` is normally a new implicit
mapping key, so the scalar stops before it. Under an explicit key (`? foo`
then `bar :`) the `:` is the key's own value indicator instead, so the line is
still key content. The scalar dropped that line and the parser stalled, so
`? foo` then `bar : baz` failed rather than yielding the key `foo bar`.
When the explicit-key marker is pending, fold the continuation line in and
stop, leaving the `:` to be scanned as the value indicator. An implicit key
keeps the previous behaviour, so a continuation ending at `:` still begins a
new key.
The test-suite rates are unchanged, since no comparable case isolates the
block form and the flow form needs separate explicit-key work, but block
explicit keys spanning lines now fold correctly. 466 tests pass.
