feat(voyage): add anchor-parser.mjs with placement validation — v4.2 Step 3
lib/parsers/anchor-parser.mjs (~190 LoC):
- parseAnchors(md) -> Anchor[] (id, target, line, snippet?, intent?)
- addAnchors(md, anchors) -> md_with_anchors
- stripAnchors(md_with_anchors) -> md (byte-identical)
- validateAnchorPlacement(md, anchors) -> errors for list-item / fenced-block / indent
Format: <!-- voyage:anchor id="ANN-NNNN" target="<slug>" line="<N>" -->
Block-level only, on its own line (col 0), blank-line separation.
Test fixture annotation-example.md with single ANN-0001 anchor — referenced by SC12 quickstart.
14 tests pass (parseAnchors, addAnchors, stripAnchors, validateAnchorPlacement).
Kjell Tore Guttormsen
fb733ae149