Update README.MD and add nano-claude-code v3.0 + original-source-code/src

- README.MD: add original-source-code and nano-claude-code sections, update
  overview table (4 subprojects), add v3.0 news entry, expand comparison table
  with memory/multi-agent/skills dimensions
- nano-claude-code v3.0: multi-agent package (multi_agent/), memory package
  (memory/), skill package (skill/) with built-in /commit and /review skills,
  context compression (compaction.py), tool registry plugin system, diff view,
  17 slash commands, 18 built-in tools, 101 tests (~5000 lines total)
- original-source-code/src: add raw TypeScript source tree (1884 files)

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

nano-claude-code/tests/test_diff_view.py

@@ -0,0 +1,50 @@
+import sys, os, tempfile
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+import pytest
+
+def test_generate_unified_diff():
+    from tools import generate_unified_diff
+    old = "line1\nline2\nline3\n"
+    new = "line1\nline2_modified\nline3\n"
+    diff = generate_unified_diff(old, new, "test.py")
+    assert "--- a/test.py" in diff
+    assert "+++ b/test.py" in diff
+    assert "-line2" in diff
+    assert "+line2_modified" in diff
+
+def test_generate_unified_diff_empty_old():
+    from tools import generate_unified_diff
+    diff = generate_unified_diff("", "new content\n", "test.py")
+    assert "+new content" in diff
+
+def test_edit_returns_diff(tmp_path):
+    from tools import _edit
+    f = tmp_path / "test.txt"
+    f.write_text("hello world\n")
+    result = _edit(str(f), "hello", "goodbye")
+    assert "-hello world" in result
+    assert "+goodbye world" in result
+
+def test_write_existing_returns_diff(tmp_path):
+    from tools import _write
+    f = tmp_path / "test.txt"
+    f.write_text("old content\n")
+    result = _write(str(f), "new content\n")
+    assert "-old content" in result
+    assert "+new content" in result
+
+def test_write_new_file_no_diff(tmp_path):
+    from tools import _write
+    f = tmp_path / "new.txt"
+    result = _write(str(f), "content\n")
+    assert "Created" in result
+    assert "---" not in result
+
+def test_diff_truncation():
+    from tools import generate_unified_diff, maybe_truncate_diff
+    old = "\n".join(f"line{i}" for i in range(200))
+    new = "\n".join(f"CHANGED{i}" for i in range(200))
+    diff = generate_unified_diff(old, new, "big.py")
+    truncated = maybe_truncate_diff(diff, max_lines=50)
+    assert "more lines" in truncated
+    assert truncated.count("\n") < 60