Support returnable zeroperl command artifact

[sureshchouksey8]

This PR builds on the open direction in #24 by @mt211211 and keeps the host-callback / returnable-command approach intact. I am submitting it as a clean branch without workflow-file changes because my available GitHub token cannot push .github/workflows/* updates.

Targeted issue: #23, especially the latest tester report on #24: indirect call to null after the prior _start, unreachable executed, and asyncify-state fixes.

What changed:

• adds a command-compatible zeroperl_command.wasm path with returnable _start
• keeps the API/reactor artifact separate from the command artifact
• avoids calling Perl global shutdown from the one-shot command wrapper, so browser/WASI shims do not immediately enter teardown/destructor paths after the script completes
• includes the Node WASI command smoke test from the existing Make host callback import opt-in #24 direction
• includes the supporting build fixes for zlib URL and ExifTool module discovery

Why:
The remaining trap appears after the command path is able to return. A plausible failure path is post-run global teardown in the browser/WASI shim rather than the script execution itself. For this command artifact, the Wasm instance is one-shot, so instance disposal can reclaim state instead of forcing Perl global teardown from _start.

Validation I could run here:

• git diff --check
• static assertion that stubs/zeroperl_main.c no longer references zeroperl_shutdown() and contains the one-shot command wrapper comment

Not run locally:

• Docker/browser build. This machine does not have Docker, Podman, or Apple container available, so reporter validation is still needed.

Credit:
This is intentionally based on the implementation/debugging already done in #24 by @mt211211. The additional change I am adding is the command-wrapper teardown avoidance for the latest indirect call to null report.

[sureshchouksey8]

/claim #23