Add git clean filter to normalize Obsidian table padding

Obsidian auto-formats markdown tables with column-aligned padding on
every file open, causing noisy git diffs. This filter strips extra
whitespace from table cells on git add/diff, keeping the repo clean.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.git-filters/clean-md-tables.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+"""Git clean filter: normalizes markdown table padding.
+
+Obsidian auto-formats tables with aligned columns (extra spaces).
+This filter strips padding to single-space format: | cell | cell |
+Handles escaped pipes (\\|) inside cells correctly.
+"""
+import sys
+import re
+
+SEPARATOR_RE = re.compile(r'^\|(\s*[-:]+[-:\s]*\|)+\s*$')
+
+
+def clean_table_row(line):
+    """Strip extra whitespace from a markdown table row, preserving escaped pipes."""
+    # Replace escaped pipes with placeholder
+    placeholder = '\x00PIPE\x00'
+    work = line.replace('\\|', placeholder)
+
+    if not work.startswith('|') or not work.rstrip().endswith('|'):
+        return line
+
+    # Check if separator row
+    if SEPARATOR_RE.match(work):
+        cells = work.strip().split('|')
+        # cells[0] and cells[-1] are empty (before first | and after last |)
+        n_cols = len(cells) - 2
+        return '|' + '|'.join(['---'] * n_cols) + '|'
+
+    # Regular row: split by |, trim each cell
+    cells = work.strip().split('|')
+    # cells[0] = '' (before first |), cells[-1] = '' (after last |)
+    result_parts = []
+    for i, cell in enumerate(cells):
+        if i == 0 or i == len(cells) - 1:
+            result_parts.append('')
+        else:
+            content = cell.strip().replace(placeholder, '\\|')
+            result_parts.append(f' {content} ')
+
+    return '|'.join(result_parts)
+
+
+for line in sys.stdin:
+    line = line.rstrip('\n').rstrip('\r')
+    if line.startswith('|'):
+        print(clean_table_row(line))
+    else:
+        print(line)