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/web.py

@@ -0,0 +1,24 @@
+"""
+    pygments.lexers.web
+    ~~~~~~~~~~~~~~~~~~~
+
+    Just export previously exported lexers.
+
+    :copyright: Copyright 2006-present by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+# ruff: noqa: F401
+from pygments.lexers.html import HtmlLexer, DtdLexer, XmlLexer, XsltLexer, \
+    HamlLexer, ScamlLexer, JadeLexer
+from pygments.lexers.css import CssLexer, SassLexer, ScssLexer
+from pygments.lexers.javascript import JavascriptLexer, LiveScriptLexer, \
+    DartLexer, TypeScriptLexer, LassoLexer, ObjectiveJLexer, CoffeeScriptLexer
+from pygments.lexers.actionscript import ActionScriptLexer, \
+    ActionScript3Lexer, MxmlLexer
+from pygments.lexers.php import PhpLexer
+from pygments.lexers.webmisc import DuelLexer, XQueryLexer, SlimLexer, QmlLexer
+from pygments.lexers.data import JsonLexer
+JSONLexer = JsonLexer  # for backwards compatibility with Pygments 1.5
+
+__all__ = []