Add configurable slides path and malformed marker detection

- project.json now supports "slides" field pointing to slides.json location
- Slide images are loaded from same directory as slides.json
- Validation detects malformed markers (missing ], extra spaces)
- Reports line numbers for each malformed marker

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

gnommo/validator.py

@@ -12,6 +12,7 @@ def validate_project(
     config: ProjectConfig,
     slides: dict[str, SlideDefinition],
     videos: dict[str, VideoSource],
+    malformed_markers: list[tuple[int, str]] = None,
 ) -> None:
     """
     Validate all parsed project data. Raises ValidationError if any issues found.
@@ -22,9 +23,19 @@ def validate_project(
     - All video files exist on disk
     - Background video exists (if specified)
     - Slide types are valid
+    - No malformed markers in manuscript
     """
     issues: list[ValidationIssue] = []
 
+    # Check for malformed markers first (these are likely typos)
+    if malformed_markers:
+        for line_num, marker_text in malformed_markers:
+            issues.append(ValidationIssue(
+                f"Malformed marker: {marker_text}",
+                project_path / "manuscript.txt",
+                line_num
+            ))
+
     # Check all manuscript markers have corresponding slides
     for marker in manuscript_markers:
         if marker not in slides:
@@ -34,15 +45,16 @@ def validate_project(
             ))
 
     # Check all slide images exist
-    media_path = project_path / "media"
-    slides_path = media_path / "slides"
+    # Slides are in the same directory as the slides.json file
+    slides_json_path = project_path / config.slides_path
+    slides_dir = slides_json_path.parent
 
     for slide_id, slide_def in slides.items():
-        image_path = slides_path / slide_def.image
+        image_path = slides_dir / slide_def.image
         if not image_path.exists():
             issues.append(ValidationIssue(
                 f"Slide image not found: {slide_def.image}",
-                project_path / "slides.json"
+                slides_json_path
             ))
 
         # Check slide type is valid