Bug

Creating a new Clojure namespace via Project view → New → Clojure namespace
sometimes creates the file under an absolute host path inside the target
directory.

Example: clicking "New namespace" on src/project_name/ and entering
test creates the file at:

src/project_name/home/username/code/clojure_proj/project_name/src/test.clj

instead of the expected:

src/project_name/test.clj

Root cause

create-file-from-template in new_file.clj built an absolute canonical
path via io/file + getCanonicalPath and then tried to strip the
directory prefix with string/replace-first.

This is fragile:

• clojure-lsp may return source-paths as file:// URIs
• VirtualFile.getPath may use a different separator than getCanonicalPath
• source-paths may be project-relative strings

When the prefix does not match, replace-first silently returns the full
absolute path, which IntelliJ then interprets as a path relative to the
target directory and recreates the whole host path tree inside it.

dir->partial-namespace had the same class of bug — if the prefix didn't
match it returned (subs filename 1) which produced nonsense namespaces
like home.username.code.proj....

Fix

Rewrite path math using java.nio.file.Path:

• Normalize URIs (file://) and separators via a helper ->path
• Use Path.startsWith for source-path detection (real segment-wise
  comparison instead of substring matching)
• Use Path.relativize to compute
  • the directory's path relative to the source root (for the default
    namespace prefix in the dialog), and
  • the namespace path relative to the directory (for the new-name
    passed to CreateFileFromTemplateAction/createFileFromTemplate)

No more string-prefix matching on raw paths.

Testing

Didn't rebuild locally (no toolchain on the machine I made the fix on).
Relying on CI + reviewer verification. Happy to iterate on review.