ci: gate improvise-gp in the wasm job (improvise-z5eg)

Verified clean by compiling for wasm32-unknown-unknown before adding.
Not in the browser bundle yet, but a candidate, and staying clean is free
now and expensive to retrofit.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EoW5BB87ZZdm96SvBTWawH

.github/workflows/ci.yml

@@ -43,6 +43,11 @@ jobs:
         run: cargo check -p improvise-io --target wasm32-unknown-unknown
       - name: improvise-command
         run: cargo check -p improvise-command --target wasm32-unknown-unknown
+      # Not in the browser bundle yet — nothing depends on improvise-gp. Gated
+      # anyway because it is a candidate (fitting a tree in the browser) and
+      # staying wasm-clean is free now, expensive to retrofit (improvise-z5eg).
+      - name: improvise-gp
+        run: cargo check -p improvise-gp --target wasm32-unknown-unknown
 
   kb:
     name: Knowledge base consistency