fix: Improve Python project detection and entrypoint resolution (#1010)

### Summary

- Simplified Python project detection to discover packages purely by
looking for directories with `__init__.py` files.
- Derived default Actor name from the Python package name.
- Added near-miss detection with actionable fix suggestions for broken
Python packages.
- Subpackage detection.
- Added 29 unit tests covering the full detection matrix.

### Python project detection

- Detect Python projects purely via package structure: directories with
valid Python identifier names containing `__init__.py`.
- Skip hidden directories (`.venv`) and underscore-prefixed directories
(`__pycache__`, `_internal`) as they shouldn't be main entrypoints.
- When `src/` is itself a package (has `__init__.py`), treat nested
directories as subpackages, not separate top-level packages.

### Actor name derivation

- For Python projects, the default Actor name is derived from the
package name.
- Entrypoint src.my_package → extracts my_package → sanitizes to
my-package.
- Entrypoint my_package → sanitizes to my-package.

### Runtime precedence

- Node.js (`package.json`) takes precedence over Python indicators when
both exist.
  
###  Error handling

- Near-miss: invalid name + `__init__.py` — suggests renaming the
directory (e.g., my-package/ → my_package/)
- Near-miss: valid name + .py files but no `__init__.py` — suggests
adding `__init__.py`
- Near-miss: invalid name + .py files but no `__init__.py` — suggests
both renaming and adding `__init__.py`
- Multiple packages — lists all found packages and guides user to ensure
only one top-level package exists
- No package and no Python files — returns Unknown (not a Python
project)

### Test plan

- 29 tests covering the full parametrized matrix: {CWD with dashes |
underscores} × {flat | src container} × {valid | invalid pkg name} ×
{`__init__.py` + .py | .py only | no .py} = 24 cases, plus 5 individual
cases:
  - JavaScript and Python coexistence (JS takes precedence)
  - Multiple flat packages error
  - Multiple packages in `src/` error
  - Loose .py files without package structure
  - No Python project at all (Unknown)
- All existing local tests pass

---

Co-Authored-By: Claude Opus 4.6 noreply@anthropic.com

Author: vdusek

src/commands/init.ts

@@ -12,7 +12,7 @@ import { useYesNoConfirm } from '../lib/hooks/user-confirmations/useYesNoConfirm
 import { createPrefilledInputFileFromInputSchema } from '../lib/input_schema.js';
 import { error, info, success, warning } from '../lib/outputs.js';
 import { wrapScrapyProject } from '../lib/projects/scrapy/wrapScrapyProject.js';
-import { setLocalConfig, setLocalEnv, validateActorName } from '../lib/utils.js';
+import { sanitizeActorName, setLocalConfig, setLocalEnv, validateActorName } from '../lib/utils.js';
 
 export class InitCommand extends ApifyCommand<typeof InitCommand> {
 	static override name = 'init' as const;
@@ -57,6 +57,20 @@ export class InitCommand extends ApifyCommand<typeof InitCommand> {
 
 		const project = projectResult.unwrap();
 
+		if (project.warnings?.length) {
+			for (const w of project.warnings) {
+				warning({ message: w });
+			}
+		}
+
+		let defaultActorName = basename(cwd);
+		if (project.type === ProjectLanguage.Python && project.entrypoint?.path) {
+			const entryPath = project.entrypoint.path;
+			// Extract the actual package name (last segment of dotted path)
+			const packageName = entryPath.includes('.') ? entryPath.split('.').pop()! : entryPath;
+			defaultActorName = sanitizeActorName(packageName);
+		}
+
 		if (project.type === ProjectLanguage.Scrapy) {
 			info({ message: 'The current directory looks like a Scrapy project. Using automatic project wrapping.' });
 			this.telemetryData.actorWrapper = 'scrapy';
@@ -100,7 +114,7 @@ export class InitCommand extends ApifyCommand<typeof InitCommand> {
 					try {
 						const answer = await useUserInput({
 							message: 'Actor name:',
-							default: basename(cwd),
+							default: defaultActorName,
 						});
 
 						validateActorName(answer);

src/commands/run.ts

@@ -130,6 +130,12 @@ export class RunCommand extends ApifyCommand<typeof RunCommand> {
 		const project = projectRuntimeResult.unwrap();
 		const { type, entrypoint: cwdEntrypoint, runtime } = project;
 
+		if (project.warnings?.length) {
+			for (const w of project.warnings) {
+				warning({ message: w });
+			}
+		}
+
 		if (type === ProjectLanguage.Unknown) {
 			throw new Error(
 				'Actor is of an unknown format.' +