feat: parse and render Obsidian cross-references (task 0005)

Model `[[wikilinks]]` and `![[transclusions]]` as distinct inline node
types sharing a `{ target, anchor?, display? }` shape, and render them:
wikilinks underlined (display text or target), transclusions as their
raw source text.

remark-wiki-link is added to the pipeline for `[[…]]`. It does not
recognise `![[…]]` embeds or split the `#anchor` from the target, so
transclusions are recovered by scanning text runs and anchors are split
in the translation layer. Its alias divider is set to `|` so Step
Reference anchors like `#rolling:2` survive.

.claude/tasks/0005-cross-references.md

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+---
+spec: core-parser
+blocked-by: 0004-richer-blocks-and-inline
+---
+
+## What to build
+
+Add Obsidian cross-references so `[[links]]` and `![[embeds]]` — including KitchenMD Step References — are typed nodes the parser surfaces and the renderer styles.
+
+In `@kitchen-md/core`, model `WikilinkNode` and `TransclusionNode`, both `{ target, anchor?, display? }`: `target` is the filename without extension, `anchor` is the part after `#` passed through verbatim, `display` is the alias after `|`.
+The node type — not a boolean flag — discriminates a reference (`[[…]]`) from an embed (`![[…]]`).
+`TransclusionNode` covers KitchenMD Step References (`![[file#section:N]]`, `![[file#N]]`), whose anchor is passed through as-is; Step Reference resolution is out of scope.
+Add remark-wiki-link to the pipeline.
+
+In `@kitchen-md/bin`, render wikilinks distinctly from surrounding prose (underline or distinct colour), using display text or the target when there is no display text.
+Render transclusions as their raw source text (e.g. `![[file#section:1]]`).
+
+## Acceptance criteria
+
+- [x] `WikilinkNode` and `TransclusionNode` share the `{ target, anchor?, display? }` shape and are distinct node types
+- [x] Wikilinks parse with a bare target, with an anchor, and with a display alias; the anchor is passed through verbatim
+- [x] Transclusions parse with a display alias and with a Step Reference anchor (`#section:N` and `#N`) passed through as-is
+- [x] `render` shows wikilinks distinctly (display text, or target when absent)
+- [x] `render` shows transclusions as their raw source text
+- [x] Core unit tests cover wikilink (bare, anchor, display) and transclusion (bare, display, Step Reference anchor)
+- [x] Renderer unit tests (ANSI stripped) cover wikilink and transclusion rendering
+
+## Implementation Notes
+
+All acceptance criteria are met, with no dropped or deferred criteria.
+The following decisions are worth recording.
+
+### remark-wiki-link handles only `[[…]]`, so transclusions are recovered separately
+
+The installed `remark-wiki-link@2.0.1` (landakram) parses `[[…]]` into `wikiLink` mdast nodes but does not recognise `![[…]]` embeds.
+The leading `!` makes remark attempt an image, which fails and leaves the whole span as literal text.
+Transclusions are therefore recovered in the translation layer by scanning each text run for `!\[\[…]]` and splitting it into text and `TransclusionNode` parts.
+This keeps the plugin in the pipeline as the spec asks while still surfacing transclusions as typed nodes.
+
+### Anchors are split in the translation layer, not by the plugin
+
+remark-wiki-link leaves the `#anchor` attached to the node's `value` and does not separate it.
+A shared `splitAnchor` helper splits `target#anchor` at the first `#` for both node types, so the anchor is passed through verbatim and the key is omitted entirely when absent.
+
+### The alias divider is set to `|`
+
+The plugin defaults its alias divider to `:`, which would consume a Step Reference anchor such as `#rolling:2`.
+It is configured with `aliasDivider: "|"` so that only a real Obsidian alias is split off, and a display alias is recorded only when it differs from the node's value.
+
+### Discriminants mirror the interface names
+
+Following task 0004's precedent for `codeSpan`, the discriminants are `"wikilink"` and `"transclusion"` — the interface names lowercased — since neither construct has an mdast counterpart to borrow a type name from.
+
+### Optional keys are omitted when absent
+
+Consistent with task 0004, `anchor` and `display` are spread in only when present rather than set to `undefined`, so parser output deep-equals the expected node shape without stray keys.
+
+### Rendering follows task 0003/0004 conventions
+
+Wikilinks render underlined, showing the display text or the target when there is no display, matching how links render (both are references).
+When a wikilink has an anchor but no display, only the target text shows — this follows the spec's wording ("display text, or the target when there is no display text") exactly.
+Transclusions render as their reconstructed raw source (`![[target#anchor|display]]`), unstyled, since resolving the embed is out of scope.
+The renderer tests assert ANSI-stripped text plus the presence of styling, never particular colours.