!Rain::S3 Run directive doubles absolute template path

[allixsenos]

Bug Description

When a template is passed to rain deploy as an absolute path, the !Rain::S3 Run directive produces a doubled path, causing fork/exec to fail with "no such file or directory".

Steps to Reproduce

1. Template at /home/user/project/myapp/template.yml contains:

   Code: !Rain::S3
     Path: dist
     Zip: true
     BucketProperty: S3Bucket
     KeyProperty: S3Key
     Run: scripts/build.sh

2. Run from /home/user/project/:

   rain deploy /home/user/project/myapp/template.yml my-stack -y

3. Rain resolves Run: scripts/build.sh relative to the template directory:
   → /home/user/project/myapp/scripts/build.sh (correct, absolute)

4. Rain then prepends the working directory to this already-absolute path:
   → /home/user/project/home/user/project/myapp/scripts/build.sh (doubled)

Error

error packaging template '/home/user/project/myapp/template.yml': fork/exec /home/user/project/home/user/project/myapp/scripts/build.sh: no such file or directory

Expected Behavior

Rain should detect that the resolved Run path is already absolute and skip prepending the working directory. The Path directive appears to have the same issue.

Workaround

Pass the template as a relative path instead of absolute:

rain deploy myapp/template.yml my-stack -y

Or run the build script externally before rain deploy and omit the Run directive.

Environment

• Rain version: latest (installed via Homebrew)
• OS: macOS (Darwin 25.3.0, arm64)