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/sqlalchemy/testing/pickleable.py

@@ -0,0 +1,155 @@
+# testing/pickleable.py
+# Copyright (C) 2005-2026 the SQLAlchemy authors and contributors
+# <see AUTHORS file>
+#
+# This module is part of SQLAlchemy and is released under
+# the MIT License: https://www.opensource.org/licenses/mit-license.php
+# mypy: ignore-errors
+
+
+"""Classes used in pickling tests, need to be at the module level for
+unpickling.
+"""
+
+from __future__ import annotations
+
+from .entities import ComparableEntity
+from ..schema import Column
+from ..types import String
+
+
+class User(ComparableEntity):
+    pass
+
+
+class Order(ComparableEntity):
+    pass
+
+
+class Dingaling(ComparableEntity):
+    pass
+
+
+class EmailUser(User):
+    pass
+
+
+class Address(ComparableEntity):
+    pass
+
+
+# TODO: these are kind of arbitrary....
+class Child1(ComparableEntity):
+    pass
+
+
+class Child2(ComparableEntity):
+    pass
+
+
+class Parent(ComparableEntity):
+    pass
+
+
+class Screen:
+    def __init__(self, obj, parent=None):
+        self.obj = obj
+        self.parent = parent
+
+
+class Mixin:
+    email_address = Column(String)
+
+
+class AddressWMixin(Mixin, ComparableEntity):
+    pass
+
+
+class Foo:
+    def __init__(self, moredata, stuff="im stuff"):
+        self.data = "im data"
+        self.stuff = stuff
+        self.moredata = moredata
+
+    __hash__ = object.__hash__
+
+    def __eq__(self, other):
+        return (
+            other.data == self.data
+            and other.stuff == self.stuff
+            and other.moredata == self.moredata
+        )
+
+
+class Bar:
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+    __hash__ = object.__hash__
+
+    def __eq__(self, other):
+        return (
+            other.__class__ is self.__class__
+            and other.x == self.x
+            and other.y == self.y
+        )
+
+    def __str__(self):
+        return "Bar(%d, %d)" % (self.x, self.y)
+
+
+class OldSchool:
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+    def __eq__(self, other):
+        return (
+            other.__class__ is self.__class__
+            and other.x == self.x
+            and other.y == self.y
+        )
+
+
+class OldSchoolWithoutCompare:
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+
+class BarWithoutCompare:
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+    def __str__(self):
+        return "Bar(%d, %d)" % (self.x, self.y)
+
+
+class NotComparable:
+    def __init__(self, data):
+        self.data = data
+
+    def __hash__(self):
+        return id(self)
+
+    def __eq__(self, other):
+        return NotImplemented
+
+    def __ne__(self, other):
+        return NotImplemented
+
+
+class BrokenComparable:
+    def __init__(self, data):
+        self.data = data
+
+    def __hash__(self):
+        return id(self)
+
+    def __eq__(self, other):
+        raise NotImplementedError
+
+    def __ne__(self, other):
+        raise NotImplementedError