test(lint): back the Vale 3.15.2 behaviour claims with a committed test

The `house-vale-3-15-2-repro` provenance entry claimed behaviours were
reproduced against purpose-built fixtures, but no fixtures existed, so
the earlier commit in this PR removed it. Commit the fixtures.

tests/test-vale-3-15-2-behaviours.sh builds its fixtures in a temp dir
and runs the real Vale. It exits 77 (skipped) when vale is missing or is
not 3.15.2. It asserts the six vale-config behaviours and the vale-run
ones (unmapped .mdx, `vale off` variants, the spelling ignore file, and
the ls-* commands never naming a rule).

Restore the entry in both sources.md files as `Research doc: none` with
`Basis:` naming the test, and re-add its source_keys. Two behaviours are
not asserted: the native-MDX suppression column (needs mdx2vast) and the
`vale sync` row that adds to Packages (needs the network). The wording in
configuration-reference.md and troubleshooting.md now says so.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EGHFJextYtVQseaHPDDhxB

plugins/lint/.apm/skills/vale-run/references/sources.md

@@ -7,3 +7,12 @@
 - **Research doc:** plugins/lint/docs/research/docs/vale/sources.md
 - **Contributing files:** SKILL.md, references/troubleshooting.md
 - **Status:** `extracted`
+
+## house-vale-3-15-2-repro
+
+- **URL:** (house-verified — reproduced against the `vale` binary by a committed test, not an external source)
+- **Description:** Behaviour of Vale 3.15.2 asserted by the committed test (purpose-built fixtures, real `vale` run), where vale.sh documents nothing or documents it wrongly: an unmapped `.mdx` needs an external `mdx2vast` binary (absent, the whole invocation exits 2 with `E100 [lintMDX]`), under `[formats] mdx = md` the HTML-comment suppression form works and the JSX-comment form does not, the `spelling` check's `ignore` paths resolve against `StylesPath` or the working directory but never against the rule file's own directory and fail silently when they resolve nowhere, `ls-config` and the other `ls-*` subcommands report styles and paths but never rules, and the `text.frontmatter.<key>` scope matrix across multi-line YAML forms. Not asserted: the native-MDX column of the suppression table, which needs `mdx2vast` installed.
+- **Research doc:** none
+- **Basis:** tests/test-vale-3-15-2-behaviours.sh
+- **Contributing files:** SKILL.md, references/troubleshooting.md
+- **Status:** `extracted`

plugins/lint/.apm/skills/vale-run/references/troubleshooting.md

@@ -1,6 +1,7 @@
 ---
 source_keys:
   - context7-websites-vale-sh
+  - house-vale-3-15-2-repro
 ---
 
 # Vale troubleshooting reference
@@ -50,8 +51,7 @@ suppression syntax:
 | `[formats]` maps `mdx = md` (what `vale-config` recommends) | none | Markdown | `<!-- vale off -->` |
 | no `mdx` mapping (native MDX) | `npm install -g mdx2vast` | MDX | `{/* vale off */}` |
 
-Key the markup to that config row, never to the file extension. Verified against Vale 3.15.2, same
-three fixtures under each config:
+Key the markup to that config row, never to the file extension. Asserted against Vale 3.15.2 by `tests/test-vale-3-15-2-behaviours.sh` (slug `house-vale-3-15-2-repro`) for the mapped column; the native-MDX column was observed with `mdx2vast` installed and is not covered by that test (it needs the binary):
 
 | File | Mapped `mdx = md` | Native MDX (`mdx2vast` installed) |
 |---|---|---|
@@ -119,7 +119,7 @@ ignore:
 **Where the file goes, and why a wrong answer is invisible.** Each entry resolves against the
 `StylesPath` root, or against the working directory `vale` is invoked from. It does **not** resolve
 against the rule file's own directory — which is the natural reading of the YAML above, since the
-path sits inside the rule, and it is wrong. Verified against Vale 3.15.2 across four fresh trees,
+path sits inside the rule, and it is wrong. Asserted against Vale 3.15.2 by the same test across four fresh trees,
 each with the same rule and the same unknown word:
 
 | Where `ignore1.txt` was placed | Result |