fix: support monochrome custom logos via logo-invert.svg filename convention (#141)

Custom logos were hardcoded as full-color, making white/monochrome logos
invisible in light mode. Adds logo-invert.svg as a higher-priority
candidate that enables the brightness filter in light mode.

AGENTS.md

@@ -640,7 +640,8 @@ ${CONTENT_HOME}/
 │   └── getting-started.md # Example: Getting Started (/pages/getting-started)
 └── media/            # Custom media files
     └── images/
-        └── logo.svg  # Custom logo (replaces default favicon and navbar/home logo)
+        ├── logo.svg          # Full-color custom logo (default)
+        └── logo-invert.svg   # Monochrome custom logo (darkened in light mode)
 ```
 
 Pages use YAML frontmatter for metadata:

README.md

@@ -480,15 +480,17 @@ Control which pages are visible in the web dashboard. Disabled features are full
 
 The web dashboard supports custom content including markdown pages and media files. Content is organized in subdirectories:
 
-Custom logo note:
-- If a custom logo file is present, the UI keeps its original colors in both light/dark themes (no automatic light-mode darkening).
+Custom logo options:
+- `logo.svg` — full-color logo, displayed as-is in both themes (no automatic darkening)
+- `logo-invert.svg` — monochrome/two-tone logo, automatically darkened in light mode for visibility
 ```
 content/
 ├── pages/     # Custom markdown pages
 │   └── about.md
 └── media/     # Custom media files
     └── images/
-        └── logo.svg   # Custom logo (replaces favicon and navbar/home logo)
+        ├── logo.svg          # Full-color custom logo (default)
+        └── logo-invert.svg   # Monochrome custom logo (darkened in light mode)
 ```
 
 **Setup:**

src/meshcore_hub/web/app.py

@@ -56,13 +56,15 @@ def _resolve_logo(media_home: Path) -> tuple[str, bool, Path | None]:
     Returns:
         tuple of (logo_url, invert_in_light_mode, resolved_path)
     """
-    custom_logo_candidates = (("logo.svg", "/media/images/logo.svg"),)
-    for filename, url in custom_logo_candidates:
+    custom_logo_candidates = (
+        ("logo-invert.svg", "/media/images/logo-invert.svg", True),
+        ("logo.svg", "/media/images/logo.svg", False),
+    )
+    for filename, url, invert_in_light_mode in custom_logo_candidates:
         path = media_home / "images" / filename
         if path.exists():
-            # Custom logos are assumed to be full-color and should not be darkened.
             cache_buster = int(path.stat().st_mtime)
-            return f"{url}?v={cache_buster}", False, path
+            return f"{url}?v={cache_buster}", invert_in_light_mode, path
 
     # Default packaged logo is monochrome and needs darkening in light mode.
     return "/static/img/logo.svg", True, None