fix(sdk): break runtime-bwrap → sdk → runtime-bwrap cycle that broke CI

Phase 2c (commit 2545e9e) added @computeragent/runtime-bwrap (+ runtime-local,
runtime-e2b, engine-claude-agent-sdk, identity-gitagentprotocol) to sdk's
devDependencies so the substrate-matrix tests could exercise them. But
runtime-bwrap already depends on sdk → cycle.

pnpm tolerates the cycle locally with a warning, ordering the builds in a way
that happens to work. CI parallelizes the cyclic packages and both fail with
TS2307 (can't resolve types of the not-yet-built sibling).

The matrix tests already use dynamic `await import(...)` inside makeSubstrate,
so the static devDeps were never load-bearing. The .test.ts file is excluded
from sdk's tsconfig (build + typecheck) — runtime resolution at test time
goes through workspace hoisting. Drop the cycle-creating devDeps.

Verified: pnpm -r build, pnpm -r typecheck, pnpm -r test all green; cyclic
workspace dependency warning gone; 349 passing / 57 skipped offline.

Author: kapaleshreyas

packages/sdk/package.json

@@ -27,11 +27,6 @@
   },
   "devDependencies": {
     "@computeragent/harness-server": "workspace:*",
-    "@computeragent/runtime-local": "workspace:*",
-    "@computeragent/runtime-bwrap": "workspace:*",
-    "@computeragent/runtime-e2b": "workspace:*",
-    "@computeragent/engine-claude-agent-sdk": "workspace:*",
-    "@computeragent/identity-gitagentprotocol": "workspace:*",
     "@computeragent/testing": "workspace:*",
     "@hono/node-server": "^1.13.0",
     "typescript": "^5.5.0",