fix(julia): drop name/uuid from Project.toml to make it environment-only (#7614)

## Summary

- First impl-generate run for `makie/skewt-logp-atmospheric` ([run
26311670534](https://github.com/MarkusNeusinger/anyplot/actions/runs/26311670534))
failed at the **Setup Julia + Makie** step. All 311 transitive deps
precompiled cleanly, then Julia tried to precompile the project itself
and bailed:
  ```
  ERROR: The following 1 direct dependency failed to precompile: anyplot
Error: Missing source file for Base.PkgId(UUID("5f9c7e1d-…"), "anyplot")
  ```
- Root cause: `Project.toml` declared `name = "anyplot"` + `uuid = …` +
`version = …`, which makes Julia treat the repo as a *package* and look
for `src/anyplot.jl`. anyplot isn't a Julia package; it just consumes
packages.
- Fix: remove `name`/`uuid`/`authors`/`version`. Turns `Project.toml`
into an *environment-only* project (the standard pattern used by Julia's
own docs/benchmark environments). `[deps]` and `[compat]` stay
untouched, so dep resolution and reproducibility are unchanged.

This was hidden during PR #7613 because the `Setup Julia + Makie`
action's smoke test only runs `using CairoMakie` and `save(...)` — Julia
only attempts to precompile the active project itself when there are
dependents being added to it, which happened on the first real
impl-generate run.

## Test plan

- [ ] CI green
- [ ] After merge: re-trigger `gh workflow run impl-generate.yml -f
specification_id=skewt-logp-atmospheric -f library=makie -f
issue_number=3802` and verify `Setup Julia + Makie` completes past
precompile.

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

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: MarkusNeusinger

Project.toml

@@ -1,10 +1,10 @@
-name = "anyplot"
-uuid = "5f9c7e1d-8b3d-4c1a-9f6e-1a2b3c4d5e6f"
-authors = ["anyplot contributors"]
-version = "0.1.0"
-
 # Julia runtime stack for the CairoMakie implementations.
 #
+# This is an *environment-only* project — no `name`/`uuid`/`version`. anyplot
+# is not a Julia package; it just consumes packages. Adding `name`/`uuid`
+# would make Julia try to precompile `anyplot` itself and fail because no
+# `src/anyplot.jl` exists.
+#
 # Reproducibility model — sibling of `renv.lock` for R:
 # - Project.toml lists the packages we depend on (this file).
 # - Manifest.toml pins the exact resolved versions across the entire