feat(phase1): add image storage utilities

- Create backend/services/image_storage.py with 4 core functions:
  - sanitize_filename(): remove unsafe chars, limit to 255 chars, convert to lowercase
  - get_unique_filename(): handle collisions with UUID suffix (format: {name}_{uuid8}_{variant}.jpg)
  - ensure_image_directories(): create /images/ root and category subdirs on startup
  - save_image(): save bytes to /images/{category}/{filename}, returns relative path
- Create comprehensive test suite (22 tests) covering all functionality
- Integrate ensure_image_directories() into FastAPI startup event
- Directory structure: /images/{category}/{filename}
- Collision handling: auto-suffix with UUID if filename exists
- All tests passing, pathlib.Path for safe operations

venv/lib/python3.12/site-packages/passlib/handlers/roundup.py

@@ -0,0 +1,29 @@
+"""passlib.handlers.roundup - Roundup issue tracker hashes"""
+#=============================================================================
+# imports
+#=============================================================================
+# core
+import logging; log = logging.getLogger(__name__)
+# site
+# pkg
+import passlib.utils.handlers as uh
+from passlib.utils.compat import u
+# local
+__all__ = [
+    "roundup_plaintext",
+    "ldap_hex_md5",
+    "ldap_hex_sha1",
+]
+#=============================================================================
+#
+#=============================================================================
+roundup_plaintext = uh.PrefixWrapper("roundup_plaintext", "plaintext",
+                                     prefix=u("{plaintext}"), lazy=True)
+
+# NOTE: these are here because they're currently only known to be used by roundup
+ldap_hex_md5 = uh.PrefixWrapper("ldap_hex_md5", "hex_md5", u("{MD5}"), lazy=True)
+ldap_hex_sha1 = uh.PrefixWrapper("ldap_hex_sha1", "hex_sha1", u("{SHA}"), lazy=True)
+
+#=============================================================================
+# eof
+#=============================================================================