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/pygments/styles/xcode.py

@@ -0,0 +1,53 @@
+"""
+    pygments.styles.xcode
+    ~~~~~~~~~~~~~~~~~~~~~
+
+    Style similar to the `Xcode` default theme.
+
+    :copyright: Copyright 2006-present by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+from pygments.style import Style
+from pygments.token import Keyword, Name, Comment, String, Error, \
+     Number, Operator, Literal
+
+
+__all__ = ['XcodeStyle']
+
+
+class XcodeStyle(Style):
+    """
+    Style similar to the Xcode default colouring theme.
+    """
+
+    name = 'xcode'
+    
+    styles = {
+        Comment:                '#177500',
+        Comment.Preproc:        '#633820',
+
+        String:                 '#C41A16',
+        String.Char:            '#2300CE',
+
+        Operator:               '#000000',
+
+        Keyword:                '#A90D91',
+
+        Name:                   '#000000',
+        Name.Attribute:         '#836C28',
+        Name.Class:             '#3F6E75',
+        Name.Function:          '#000000',
+        Name.Builtin:           '#A90D91',
+        # In Obj-C code this token is used to colour Cocoa types
+        Name.Builtin.Pseudo:    '#5B269A',
+        Name.Variable:          '#000000',
+        Name.Tag:               '#000000',
+        Name.Decorator:         '#000000',
+        # Workaround for a BUG here: lexer treats multiline method signatres as labels
+        Name.Label:             '#000000',
+
+        Literal:                '#1C01CE',
+        Number:                 '#1C01CE',
+        Error:                  '#000000',
+    }