fix(#2948): wire spike --wrap-up flag dispatch (#2951)

* fix(#2948): wire spike --wrap-up flag dispatch

Add dispatch block to commands/gsd/spike.md so that /gsd-spike --wrap-up
routes to the spike-wrap-up workflow instead of silently no-oping. Also
add spike-wrap-up.md to execution_context so the runtime can load it, and
update both companion references in workflows/spike.md from the deleted
/gsd-spike-wrap-up entry-point to /gsd-spike --wrap-up.

Fixes #2948

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* test(#2948): rewrite dispatch test using parseFrontmatter + section extraction

Replace raw fs.readFileSync + text.includes() / regex assertions with structural
parsing: parseFrontmatter extracts the YAML frontmatter fields and _body,
extractSection pulls named XML blocks, and parseExecutionContextRefs resolves
the @-prefixed workflow references. Assertions now target the argument-hint
frontmatter field, the execution_context @-ref list, and the routing text within
<context>/<process> sections — not arbitrary substrings in the raw file.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* test(#2948): tighten dispatch assertion to line-level rule check

Replace the co-occurrence check (dispatchText.includes('--wrap-up') &&
dispatchText.includes('spike-wrap-up')) with line-level assertions that parse
the <process> section's rules array, find the exact '- If it is `--wrap-up`:'
line, verify it includes 'strip the flag' and 'spike-wrap-up', and assert the
'- Otherwise:' fallback still routes to the spike workflow.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* test(#2948): anchor parseFrontmatter to line 0 to avoid mid-file --- delimiters

parseFrontmatter was scanning the whole file for the first two '---' lines,
which can match a mid-document horizontal rule as the opening delimiter.
Now requires lines[0].trim() === '---'; returns { _body: content } for files
with no frontmatter, and searches for the closing '---' from line 1 onward.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

commands/gsd/spike.md

@@ -30,6 +30,7 @@ Does not require `/gsd-new-project` — auto-creates `.planning/spikes/` if need
 
 <execution_context>
 @~/.claude/get-shit-done/workflows/spike.md
+@~/.claude/get-shit-done/workflows/spike-wrap-up.md
 @~/.claude/get-shit-done/references/ui-brand.md
 </execution_context>
 
@@ -47,6 +48,9 @@ Idea: $ARGUMENTS
 </context>
 
 <process>
-Execute the spike workflow from @~/.claude/get-shit-done/workflows/spike.md end-to-end.
+Parse the first token of $ARGUMENTS:
+- If it is `--wrap-up`: strip the flag, execute the spike-wrap-up workflow from @~/.claude/get-shit-done/workflows/spike-wrap-up.md.
+- Otherwise: pass all of $ARGUMENTS as the idea to the spike workflow from @~/.claude/get-shit-done/workflows/spike.md end-to-end.
+
 Preserve all workflow gates (prior spike check, decomposition, research, risk ordering, observability assessment, verification, MANIFEST updates, commit patterns).
 </process>