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/srcinfo.py

@@ -0,0 +1,62 @@
+"""
+    pygments.lexers.srcinfo
+    ~~~~~~~~~~~~~~~~~~~~~~~
+
+    Lexers for .SRCINFO files used by Arch Linux Packages.
+
+    The description of the format can be found in the wiki:
+    https://wiki.archlinux.org/title/.SRCINFO
+
+    :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 Text, Comment, Keyword, Name, Operator, Whitespace
+
+__all__ = ['SrcinfoLexer']
+
+keywords = (
+    'pkgbase', 'pkgname',
+    'pkgver', 'pkgrel', 'epoch',
+    'pkgdesc', 'url', 'install', 'changelog',
+    'arch', 'groups', 'license', 'noextract', 'options', 'backup',
+    'validpgpkeys',
+)
+
+architecture_dependent_keywords = (
+    'source', 'depends', 'checkdepends', 'makedepends', 'optdepends',
+    'provides', 'conflicts', 'replaces',
+    'md5sums', 'sha1sums', 'sha224sums', 'sha256sums', 'sha384sums',
+    'sha512sums',
+)
+
+
+class SrcinfoLexer(RegexLexer):
+    """Lexer for .SRCINFO files used by Arch Linux Packages.
+    """
+
+    name = 'Srcinfo'
+    aliases = ['srcinfo']
+    filenames = ['.SRCINFO']
+    url = 'https://wiki.archlinux.org/title/.SRCINFO'
+    version_added = '2.11'
+
+    tokens = {
+        'root': [
+            (r'\s+', Whitespace),
+            (r'#.*', Comment.Single),
+            (words(keywords), Keyword, 'assignment'),
+            (words(architecture_dependent_keywords, suffix=r'_\w+'),
+             Keyword, 'assignment'),
+            (r'\w+', Name.Variable, 'assignment'),
+        ],
+        'assignment': [
+            (r' +', Whitespace),
+            (r'=', Operator, 'value'),
+        ],
+        'value': [
+            (r' +', Whitespace),
+            (r'.*', Text, '#pop:2'),
+        ],
+    }