Python: Isolate openrewrite package by version and add recipeInstallDir to Builder

When multiple CLI versions share the same home directory, they conflict
over the openrewrite Python package. This change resolves that by:

1. Resolving a version-specific subdirectory under pipPackagesPath
   (e.g., `<basePath>/0.5.3/`) so different openrewrite versions
   don't overwrite each other. Two CLI versions shipping the same
   openrewrite package version share the directory.

2. Adding a `recipeInstallDir` builder method for a separate shared
   directory containing user-installed recipe packages (added to
   PYTHONPATH alongside the version-specific openrewrite directory).

Author: knutwannheden

rewrite-python/src/main/java/org/openrewrite/python/rpc/PythonRewriteRpc.java

@@ -379,6 +379,7 @@ public static class Builder implements Supplier<PythonRewriteRpc> {
         private Path pythonPath = findDefaultPythonPath();
         private @Nullable Path log;
         private @Nullable Path pipPackagesPath;
+        private @Nullable Path recipeInstallDir;
 
         private static Path findDefaultPythonPath() {
             // Try to find a venv in the project structure
@@ -501,6 +502,19 @@ public Builder pipPackagesPath(@Nullable Path pipPackagesPath) {
             return this;
         }
 
+        /**
+         * Set the directory where user-installed recipe packages live.
+         * This directory is added to PYTHONPATH so the RPC server can
+         * find recipe packages installed via pip.
+         *
+         * @param recipeInstallDir The directory containing recipe pip packages
+         * @return This builder
+         */
+        public Builder recipeInstallDir(@Nullable Path recipeInstallDir) {
+            this.recipeInstallDir = recipeInstallDir;
+            return this;
+        }
+
         /**
          * Set the Python language version to parse.
          * <p>
@@ -531,8 +545,12 @@ public PythonRewriteRpc get() {
             boolean interpreterHasRewrite = isDevBuild && pipPackagesPath != null && canImportRewrite(pythonPath);
             boolean usePipPackagesPath = pipPackagesPath != null && !interpreterHasRewrite;
 
+            // Resolve version-specific subdirectory under pipPackagesPath
+            Path resolvedPipPackagesPath = null;
             if (usePipPackagesPath) {
-                bootstrapOpenrewrite(pipPackagesPath);
+                String versionDir = isDevBuild ? "dev" : version;
+                resolvedPipPackagesPath = pipPackagesPath.resolve(versionDir);
+                bootstrapOpenrewrite(resolvedPipPackagesPath);
             }
 
             Stream<@Nullable String> cmd;
@@ -562,8 +580,13 @@ public PythonRewriteRpc get() {
             List<String> pythonPathParts = new ArrayList<>();
 
             // Add pip packages path if the interpreter doesn't already have rewrite
-            if (usePipPackagesPath) {
-                pythonPathParts.add(pipPackagesPath.toAbsolutePath().normalize().toString());
+            if (resolvedPipPackagesPath != null) {
+                pythonPathParts.add(resolvedPipPackagesPath.toAbsolutePath().normalize().toString());
+            }
+
+            // Add recipe install directory to PYTHONPATH
+            if (recipeInstallDir != null) {
+                pythonPathParts.add(recipeInstallDir.toAbsolutePath().normalize().toString());
             }
 
             // If debug source path is set, use it