fix(#622): make graph.html copy optional in /gsd-graphify build chain (#634)

* fix(#622): make graph.html copy optional in /gsd-graphify build chain

The Step 3 shell chain in commands/gsd/graphify.md copied graphify-out/graph.html
with an unconditional `cp` linked by `&&`. When a graph exceeds graphify's HTML
viz node limit (default 5000), `graphify update .` deliberately omits graph.html,
so the `cp` failed with "cannot stat" and aborted the chain — skipping the
GRAPH_REPORT.md copy, the diff-snapshot write, and the status report, and
reporting BUILD FAILED even though the graph data was rebuilt successfully.

Guard the graph.html copy with `{ [ -f graphify-out/graph.html ] && cp ... || true; }`,
mirroring the already-correct tolerant copy in hooks/lib/gsd-graphify-rebuild.sh.
A skipped optional HTML artifact no longer aborts the chain.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* chore(#622): add changeset for graph.html optional-copy fix

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* test(#622): CRLF-tolerant fence regex + allowlist the new graphify test

Two CI guards flagged the new regression test:
- windows-test-parity (fenceRegexLiteralNewline): the block-extraction regex
  matched ```bash with a literal \n, which breaks on Windows CRLF checkouts.
  Use ```bash\r?\n per the guard's sanctioned fix.
- lint-test-file-count: the new file is a 5th test in the grapify bucket
  (cap 2, grandfathered at 4). Add it to the graphify allowlist files array
  and give the entry a real tracking issue (TBD -> 622).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

.changeset/rapid-voles-hop.md

@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 634
+---
+**`/gsd-graphify build` no longer fails when the graph is too large for an HTML visualization** — when a graph exceeds graphify's HTML viz node limit (default 5000) the `graph.html` artifact is intentionally skipped; the build pipeline now tolerates its absence instead of aborting, so `graph.json`, `GRAPH_REPORT.md`, the diff snapshot, and the status report all still complete.