fix(release): configure release workflow for npm publishing

- Delete existing release before creating new one to avoid conflicts
- Remove llmx-responses-api-proxy from dotslash config (not needed)
- Add 'Create GitHub Release' step to upload platform binaries
- Configure npm authentication by writing token to setup-node's .npmrc
- Use internal package identifier 'llmx' in workflow scripts

This fixes the release workflow to properly:
1. Clean up previous failed releases
2. Create GitHub release with all platform binaries
3. Add DotSlash manifest file (llmx) without conflicts
4. Publish to npm as @valknarthing/llmx with proper authentication

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

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

.github/dotslash-config.json

@@ -27,34 +27,6 @@
           "path": "llmx.exe"
         }
       }
-    },
-    "llmx-responses-api-proxy": {
-      "platforms": {
-        "macos-aarch64": {
-          "regex": "^llmx-responses-api-proxy-aarch64-apple-darwin\\.zst$",
-          "path": "llmx-responses-api-proxy"
-        },
-        "macos-x86_64": {
-          "regex": "^llmx-responses-api-proxy-x86_64-apple-darwin\\.zst$",
-          "path": "llmx-responses-api-proxy"
-        },
-        "linux-x86_64": {
-          "regex": "^llmx-responses-api-proxy-x86_64-unknown-linux-musl\\.zst$",
-          "path": "llmx-responses-api-proxy"
-        },
-        "linux-aarch64": {
-          "regex": "^llmx-responses-api-proxy-aarch64-unknown-linux-musl\\.zst$",
-          "path": "llmx-responses-api-proxy"
-        },
-        "windows-x86_64": {
-          "regex": "^llmx-responses-api-proxy-x86_64-pc-windows-msvc\\.exe\\.zst$",
-          "path": "llmx-responses-api-proxy.exe"
-        },
-        "windows-aarch64": {
-          "regex": "^llmx-responses-api-proxy-aarch64-pc-windows-msvc\\.exe\\.zst$",
-          "path": "llmx-responses-api-proxy.exe"
-        }
-      }
     }
   }
 }