Fix: Make CUSTOM_TEMPLATES_DIR configurable again (#1725)

## Summary

Resolves #1484 where CUSTOM_TEMPLATES_DIR configuration was being
ignored.

The setting was previously removed from ServerConfig and hardcoded as a
constant, preventing users from customizing the templates directory
location.

## Changes

- Added CUSTOM_TEMPLATES_DIR field to StorageConfig in common.py
- Updated settings.py to use STORAGE_CONFIG.CUSTOM_TEMPLATES_DIR
- Updated paths.py to use configurable value in version output

## Usage

Users can now configure the custom templates directory via:
- ArchiveBox.conf: `CUSTOM_TEMPLATES_DIR = ./custom_templates`
- Environment variable: `export CUSTOM_TEMPLATES_DIR=/path/to/templates`
- Defaults to DATA_DIR/user_templates if not configured

Generated with [Claude Code](https://claude.ai/code)

<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Restores CUSTOM_TEMPLATES_DIR configurability so users can override the
templates directory. Fixes issue #1484 and updates the app to
consistently use the configured path.

- **Bug Fixes**
  - Added CUSTOM_TEMPLATES_DIR to StorageConfig.
- Updated settings.py and paths.py to read
STORAGE_CONFIG.CUSTOM_TEMPLATES_DIR.

- **Migration**
  - Configure via ArchiveBox.conf or the CUSTOM_TEMPLATES_DIR env var.
  - Defaults to DATA_DIR/user_templates if not set.

<sup>Written for commit 329d185d95.
Summary will update automatically on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

archivebox/core/settings.py

@@ -11,7 +11,7 @@ from django.utils.crypto import get_random_string
 import archivebox
 
 from archivebox.config import DATA_DIR, PACKAGE_DIR, ARCHIVE_DIR, CONSTANTS  # noqa
-from archivebox.config.common import SHELL_CONFIG, SERVER_CONFIG  # noqa
+from archivebox.config.common import SHELL_CONFIG, SERVER_CONFIG, STORAGE_CONFIG  # noqa
 
 
 IS_MIGRATING = "makemigrations" in sys.argv[:3] or "migrate" in sys.argv[:3]
@@ -116,9 +116,9 @@ AUTHENTICATION_BACKENDS = [
 
 STATIC_URL = "/static/"
 TEMPLATES_DIR_NAME = "templates"
-CUSTOM_TEMPLATES_ENABLED = os.path.isdir(CONSTANTS.CUSTOM_TEMPLATES_DIR) and os.access(CONSTANTS.CUSTOM_TEMPLATES_DIR, os.R_OK)
+CUSTOM_TEMPLATES_ENABLED = os.path.isdir(STORAGE_CONFIG.CUSTOM_TEMPLATES_DIR) and os.access(STORAGE_CONFIG.CUSTOM_TEMPLATES_DIR, os.R_OK)
 STATICFILES_DIRS = [
-    *([str(CONSTANTS.CUSTOM_TEMPLATES_DIR / "static")] if CUSTOM_TEMPLATES_ENABLED else []),
+    *([str(STORAGE_CONFIG.CUSTOM_TEMPLATES_DIR / "static")] if CUSTOM_TEMPLATES_ENABLED else []),
     # *[
     #     str(plugin_dir / 'static')
     #     for plugin_dir in PLUGIN_DIRS.values()
@@ -129,7 +129,7 @@ STATICFILES_DIRS = [
 ]
 
 TEMPLATE_DIRS = [
-    *([str(CONSTANTS.CUSTOM_TEMPLATES_DIR)] if CUSTOM_TEMPLATES_ENABLED else []),
+    *([str(STORAGE_CONFIG.CUSTOM_TEMPLATES_DIR)] if CUSTOM_TEMPLATES_ENABLED else []),
     # *[
     #     str(plugin_dir / 'templates')
     #     for plugin_dir in PLUGIN_DIRS.values()