feat: add @tpmjs/registrySearch and @tpmjs/registryExecute SDK packages

- Create @tpmjs/registrySearch package for searching tool registry
- Create @tpmjs/registryExecute package for executing tools via sandbox
- Support self-hosted registries via TPMJS_API_URL and TPMJS_EXECUTOR_URL env vars
- Add /sdk documentation page with usage examples and architecture
- Add SDK link to navigation menu
- Include design doc for registry SDK architecture

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

pnpm-lock.yaml

@@ -131,10 +131,10 @@ importers:
         version: 10.4.22(postcss@8.5.6)
       eslint:
         specifier: ^9.39.1
-        version: 9.39.1(jiti@2.6.1)
+        version: 9.39.1(jiti@1.21.7)
       eslint-config-next:
         specifier: ^16.0.4
-        version: 16.0.4(eslint@9.39.1(jiti@2.6.1))(typescript@5.9.3)
+        version: 16.0.4(eslint@9.39.1(jiti@1.21.7))(typescript@5.9.3)
       postcss:
         specifier: ^8.5.1
         version: 8.5.6
@@ -249,10 +249,10 @@ importers:
         version: 10.4.22(postcss@8.5.6)
       eslint:
         specifier: ^9.39.1
-        version: 9.39.1(jiti@1.21.7)
+        version: 9.39.1(jiti@2.6.1)
       eslint-config-next:
         specifier: ^16.0.4
-        version: 16.0.4(eslint@9.39.1(jiti@1.21.7))(typescript@5.9.3)
+        version: 16.0.4(eslint@9.39.1(jiti@2.6.1))(typescript@5.9.3)
       postcss:
         specifier: ^8.5.1
         version: 8.5.6
@@ -600,6 +600,32 @@ importers:
         specifier: ^5.9.3
         version: 5.9.3
 
+  packages/tools/registryExecute:
+    dependencies:
+      ai:
+        specifier: 6.0.0-beta.124
+        version: 6.0.0-beta.124(effect@3.18.4)(zod@4.1.13)
+    devDependencies:
+      '@tpmjs/tsconfig':
+        specifier: workspace:*
+        version: link:../../config/tsconfig
+      typescript:
+        specifier: ^5.7.2
+        version: 5.9.3
+
+  packages/tools/registrySearch:
+    dependencies:
+      ai:
+        specifier: 6.0.0-beta.124
+        version: 6.0.0-beta.124(effect@3.18.4)(zod@4.1.13)
+    devDependencies:
+      '@tpmjs/tsconfig':
+        specifier: workspace:*
+        version: link:../../config/tsconfig
+      typescript:
+        specifier: ^5.7.2
+        version: 5.9.3
+
   packages/tools/search-registry:
     dependencies:
       ai: