`{{url|alt|key="quoted value"}}` syntax was already parsed end-to-end
through to `TransclusionNode::attrs`, but the value retained the
surrounding `"…"` (or `'…'`) characters verbatim. The HTML renderer
then escaped them into `"`, producing `style=""border: 1px""`
instead of clean `style="border: 1px"`.
Extracted a small `insert_attr` helper that splits on `=`, trims, and
strips matching single- or double-quote pairs from the value before
inserting. Unquoted values pass through unchanged.
Tests: 4 new in crates/nuwiki-core/tests/transclusion_attrs.rs
covering double-quote stripping, single-quote stripping, unquoted
pass-through, and the clean-HTML rendering shape (no `"`).
Note: this commit covers the "transclusion attrs" half of the
original Cluster 8 audit. The "multi-line list-item continuation
paragraphs" half requires lexer + parser changes (continuation lines
indented past the marker should attach to the prior list item
instead of becoming a sibling paragraph) and is deferred.
Gates: 429 Rust / 39 Neovim / 12 Vim.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
