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/rego.py

@@ -0,0 +1,57 @@
+"""
+    pygments.lexers.rego
+    ~~~~~~~~~~~~~~~~~~~~
+
+    Lexers for the Rego policy languages.
+
+    :copyright: Copyright 2006-present by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+from pygments.lexer import RegexLexer, words
+from pygments.token import Comment, Operator, Keyword, Name, String, Number, Punctuation, Whitespace
+
+class RegoLexer(RegexLexer):
+    """
+    For Rego source.
+    """
+    name = 'Rego'
+    url = 'https://www.openpolicyagent.org/docs/latest/policy-language/'
+    filenames = ['*.rego']
+    aliases = ['rego']
+    mimetypes = ['text/x-rego']
+    version_added = '2.19'
+
+    reserved_words = (
+        'as', 'contains', 'data', 'default', 'else', 'every', 'false',
+        'if', 'in', 'import', 'package', 'not', 'null',
+        'some', 'true', 'with'
+    )
+
+    builtins = (
+        # https://www.openpolicyagent.org/docs/latest/philosophy/#the-opa-document-model
+        'data',  # Global variable for accessing base and virtual documents
+        'input', # Represents synchronously pushed base documents
+    )
+
+    tokens = {
+        'root': [
+            (r'\n', Whitespace),
+            (r'\s+', Whitespace),
+            (r'#.*?$', Comment.Single),
+            (words(reserved_words, suffix=r'\b'), Keyword),
+            (words(builtins, suffix=r'\b'), Name.Builtin),
+            (r'[a-zA-Z_][a-zA-Z0-9_]*', Name),
+            (r'"(\\\\|\\"|[^"])*"', String.Double),
+            (r'`[^`]*`', String.Backtick),
+            (r'-?\d+(\.\d+)?', Number),
+            (r'(==|!=|<=|>=|:=)', Operator),  # Compound operators
+            (r'[=<>+\-*/%&|]', Operator),     # Single-character operators
+            (r'[\[\]{}(),.:;]', Punctuation),
+        ]
+    }
+
+__all__ = ['RegoLexer']
+
+
+