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/lexers/procfile.py

@@ -0,0 +1,41 @@
+"""
+    pygments.lexers.procfile
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Lexer for Procfile file format.
+
+    :copyright: Copyright 2006-present by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+from pygments.lexer import RegexLexer, bygroups
+from pygments.token import Name, Number, String, Text, Punctuation
+
+__all__ = ["ProcfileLexer"]
+
+
+class ProcfileLexer(RegexLexer):
+    """
+    Lexer for Procfile file format.
+
+    The format is used to run processes on Heroku or is used by Foreman or
+    Honcho tools.
+    """
+    name = 'Procfile'
+    url = 'https://devcenter.heroku.com/articles/procfile#procfile-format'
+    aliases = ['procfile']
+    filenames = ['Procfile']
+    version_added = '2.10'
+
+    tokens = {
+        'root': [
+            (r'^([a-z]+)(:)', bygroups(Name.Label, Punctuation)),
+            (r'\s+', Text.Whitespace),
+            (r'"[^"]*"', String),
+            (r"'[^']*'", String),
+            (r'[0-9]+', Number.Integer),
+            (r'\$[a-zA-Z_][\w]*', Name.Variable),
+            (r'(\w+)(=)(\w+)', bygroups(Name.Variable, Punctuation, String)),
+            (r'([\w\-\./]+)', Text),
+        ],
+    }