🎨 Palette: Improve table accessibility and numeric alignment

.jules/palette.md

@@ -19,3 +19,7 @@
 ## 2024-07-13 - CLI Debugging Stack Traces
 **Learning:** Adding a `FAST_MLSIRM_DEBUG` bypass to user-friendly `try/except` blocks is crucial for DX. Otherwise, unexpected runtime errors during development will be swallowed into generic stderr messages, hiding the stack trace needed to actually fix the bug.
 **Action:** When adding `try-except` blocks to Python CLI subcommands to improve Developer Experience (DX) by preventing raw tracebacks for users, include a debug bypass (e.g., `if os.environ.get("FAST_MLSIRM_DEBUG"): raise`) in *all* catch blocks (including `RuntimeError` and `Exception`) to ensure tracebacks aren't swallowed during local development and debugging.
+
+## 2024-07-14 - Table Accessibility and Tabular Numbers
+**Learning:** Data-heavy HTML tables (like fit diagnostics) present numbers that are hard to compare visually if they are not vertically aligned. Additionally, screen readers need row headers (`<th scope="row">`) to accurately announce data context when moving horizontally across a row. Modifying cell types requires cascading those changes to CSS selectors (`thead th, tbody th, td`) to avoid breaking base styles.
+**Action:** Always use `<th scope="row">` for the first identifying column in HTML tables and apply `font-variant-numeric: tabular-nums;` across all table cells to guarantee readable alignment and standard accessibility. Explicitly update shared table cell CSS selectors when introducing new tag types to prevent visual regressions.

python/fast_mlsirm/report.py

@@ -318,8 +318,10 @@ def _table(rows: list[dict[str, Any]], *, label: str, limit: int = 12) -> str:
     body_rows = []
     for row in rows[:limit]:
         cells = "".join(
+            f'<th scope="row">{escape(_format_value(row.get(column, "")))}</th>'
+            if i == 0 else
             f"<td>{escape(_format_value(row.get(column, '')))}</td>"
-            for column in columns
+            for i, column in enumerate(columns)
         )
         body_rows.append(f"<tr>{cells}</tr>")
 
@@ -679,20 +681,26 @@ def _css() -> str:
   border: 0;
 }
 
-th,
+thead th,
+tbody th,
 td {
   padding: 10px 12px;
   text-align: left;
   border-bottom: 1px solid var(--line);
   white-space: nowrap;
+  font-variant-numeric: tabular-nums;
 }
 
-th {
+thead th {
   background: #f1f4ef;
   color: #2f3437;
   font-size: 0.8rem;
 }
 
+tbody th {
+  font-weight: normal;
+}
+
 tr:last-child td {
   border-bottom: 0;
 }