test: regenerate golden fixtures + size baselines for the example/doc edits

execute-phase.md and gsd-ai-researcher.md are installed artifacts; their edits
shift install hashes and file sizes. Diff is scoped to those two files' hashes.

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

tests/fixtures/golden-install-parity/opencode.json

@@ -2,7 +2,7 @@
   ".gsd-profile": "0e716a5fef4e6dc1",
   ".gsd/defaults.json": "560664b045e645cb",
   "agents/gsd-advisor-researcher.md": "fc4eba63daf0b1ee",
-  "agents/gsd-ai-researcher.md": "fb47a65999c957d0",
+  "agents/gsd-ai-researcher.md": "28a05307dad84020",
   "agents/gsd-assumptions-analyzer.md": "cc0dbbd41e0a77a5",
   "agents/gsd-code-fixer.md": "aa353a2a42b27981",
   "agents/gsd-code-reviewer.md": "70deeb7ac7caf384",
@@ -296,7 +296,7 @@
   "gsd-core/workflows/docs-update.md": "93e969c3afb446a0",
   "gsd-core/workflows/edit-phase.md": "ed948a400a0146c7",
   "gsd-core/workflows/eval-review.md": "1ba1af74a43c07db",
-  "gsd-core/workflows/execute-phase.md": "54846f6fffad0cea",
+  "gsd-core/workflows/execute-phase.md": "f0ca3839e0d0cf8b",
   "gsd-core/workflows/execute-phase/steps/codebase-drift-gate.md": "a640b093a5a7b028",
   "gsd-core/workflows/execute-phase/steps/per-plan-worktree-gate.md": "7ebb7d1af6082028",
   "gsd-core/workflows/execute-phase/steps/post-merge-gate.md": "8b42f5df1a2c231f",