feat(nushell): add cached nu_scripts completions bootstrap

- add pj completion command to clone/update nu_scripts cache

- load fixed custom-completions for git/ssh/cargo/uv/rustup from cache

- ignore nushell/cache contents in git while keeping placeholder .gitignore

- source pj_completions at startup and align prompt indicators/newline behavior

nushell/modules/pj_completions.nu

@@ -1,3 +1,75 @@
+def "pj completion" [
+    --update(-u) # Pull latest changes when repo already exists.
+    --force(-f) # Re-clone even when repo already exists.
+] {
+    let repo_url = "https://github.com/nushell/nu_scripts.git"
+    let cache_dir = if ('NU_POLYJUICE_PATH' in $env) {
+        ($env.NU_POLYJUICE_PATH | path join 'cache')
+    } else {
+        (pwd | path join 'nushell' 'cache')
+    }
+    let repo_dir = ($cache_dir | path join 'nu_scripts')
+    let completion_dir = ($repo_dir | path join 'custom-completions')
+
+    if (which git | is-empty) {
+        error make {
+            msg: "`git` command is required for pj completion"
+            help: "Install Git first, then run `pj completion` again."
+        }
+    }
+
+    mkdir $cache_dir
+
+    if $force {
+        if ($repo_dir | path exists) {
+            rm -rf $repo_dir
+        }
+    }
+
+    if not ($repo_dir | path exists) {
+        print "[pj completion] nu_scripts cache not found, cloning..."
+        ^git clone $repo_url $repo_dir
+    } else {
+        if not (($repo_dir | path join '.git') | path exists) {
+            print "[pj completion] existing cache is not a git repo, re-cloning..."
+            rm -rf $repo_dir
+            ^git clone $repo_url $repo_dir
+        } else if $update {
+            print "[pj completion] cache exists, updating..."
+            ^git -C $repo_dir pull --ff-only
+        }
+    }
+
+    if not ($completion_dir | path exists) {
+        error make {
+            msg: "nu_scripts cloned, but custom-completions directory is missing"
+            help: $"Check repository content under ($repo_dir)."
+        }
+    }
+
+    let required = [
+        ($completion_dir | path join 'git' 'git-completions.nu')
+        ($completion_dir | path join 'ssh' 'ssh-completions.nu')
+        ($completion_dir | path join 'cargo' 'cargo-completions.nu')
+        ($completion_dir | path join 'uv' 'uv-completions.nu')
+        ($completion_dir | path join 'rustup' 'rustup-completions.nu')
+    ]
+
+    let missing = ($required | where {|f| not ($f | path exists) })
+    if not ($missing | is-empty) {
+        print "[pj completion] warning: some required completion files are missing:"
+        $missing | each {|f| print $"  - ($f)" }
+    }
+
+    print "[pj completion] ok"
+    {
+        cache_dir: $cache_dir
+        repo_dir: $repo_dir
+        completion_dir: $completion_dir
+        missing_files: $missing
+    }
+}
+
 export-env {
     $env.config = {
         completions: {
@@ -12,3 +84,37 @@ export-env {
         }
     }
 }
+
+const pj_module_dir = (path self | path dirname)
+
+const git_completion = if (($pj_module_dir | path join '..' 'cache' 'nu_scripts' 'custom-completions' 'git' 'git-completions.nu') | path exists) {
+    ($pj_module_dir | path join '..' 'cache' 'nu_scripts' 'custom-completions' 'git' 'git-completions.nu')
+} else {
+    null
+}
+const ssh_completion = if (($pj_module_dir | path join '..' 'cache' 'nu_scripts' 'custom-completions' 'ssh' 'ssh-completions.nu') | path exists) {
+    ($pj_module_dir | path join '..' 'cache' 'nu_scripts' 'custom-completions' 'ssh' 'ssh-completions.nu')
+} else {
+    null
+}
+const cargo_completion = if (($pj_module_dir | path join '..' 'cache' 'nu_scripts' 'custom-completions' 'cargo' 'cargo-completions.nu') | path exists) {
+    ($pj_module_dir | path join '..' 'cache' 'nu_scripts' 'custom-completions' 'cargo' 'cargo-completions.nu')
+} else {
+    null
+}
+const uv_completion = if (($pj_module_dir | path join '..' 'cache' 'nu_scripts' 'custom-completions' 'uv' 'uv-completions.nu') | path exists) {
+    ($pj_module_dir | path join '..' 'cache' 'nu_scripts' 'custom-completions' 'uv' 'uv-completions.nu')
+} else {
+    null
+}
+const rustup_completion = if (($pj_module_dir | path join '..' 'cache' 'nu_scripts' 'custom-completions' 'rustup' 'rustup-completions.nu') | path exists) {
+    ($pj_module_dir | path join '..' 'cache' 'nu_scripts' 'custom-completions' 'rustup' 'rustup-completions.nu')
+} else {
+    null
+}
+
+use $git_completion *
+use $ssh_completion *
+use $cargo_completion *
+use $uv_completion *
+use $rustup_completion *