Reconsider location of (`cargo miden new`) template code.

## Background

Opening this because the project template moved into this repo, which I ran into while updating everything to v0.16. I suppose the motivation behind that was "cargo miden new" depending on that code directly, so moving it to the compiler repo makes the release coherent.

## Downstream use of project template

**Submodule of `0xMiden/agentic-template`:**
That repo pins a specific `project-template` commit and composes it with a frontend template into one agent-facing workspace, with parent-level hooks and skills that reference the submodule's paths.

**It is a repo people clone:**
I think there is real value in the code behind `cargo miden new` being visible as a standalone open-source template rather than only reachable through a CLI flag. Not every dev may start from `cargo miden new`, and some are not aware of the tooling yet.

## Complications with the new code placement

A git submodule cannot point at a subdirectory of another repo, so `agentic-template` cannot consume `extra/templates/project` directly.

**If the code stays here, the workarounds I can see workaround reolve around creating scripts to import the compiler template code:**

- A script in the standalone repo that pulls `project/` from the `templates/v*` release, with a version check using the sh.
- Or `agentic-template` doing that directly at setup, either the same pull or `cargo miden new`, instead of pinning a submodule.

Both work, but then the standalone repo only holds generated output, which will drift. And the second one loses the pinned commit, so agent runs against it are no longer reproducible.

## Ask

Would you be open to moving the template code back to the standalone repo?

Is keeping it standalone actually complex on your side, or would that be fine?

For me the current placement is the harder option for the `agentic-template` integration.

FYI, I opened a PR to migrate the `project-template` code for v16. Until we have finalized an approach going forward with what to do with the template code, would you mind approving the PR so that I can merge it and release v16 of the `agentic-template`? Just so that that is unblocked for now. @greenhat

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Tagging @greenhat and @bitwalker for request for comment.

The issue concerns the location of the project template used by `cargo miden new`, currently in `extra/templates/project`. Review the template's current structure and its integration with the `agentic-template` submodule. Understand the release process and how the CLI fetches the template. Determine the impact of moving the template code back to a standalone repository versus keeping it in the compiler repo.

Scritto dal modello di indicizzazione a partire dal testo della issue.