test: reorganize test structure and add missing unit tests

Reorganize flat tests/ directory to mirror source code structure
(tools/, gateway/, hermes_cli/, integration/). Add 11 new test files
covering previously untested modules: registry, patch_parser,
fuzzy_match, todo_tool, approval, file_tools, gateway session/config/
delivery, and hermes_cli config/models. Total: 147 unit tests passing,
9 integration tests gated behind pytest marker.

tests/tools/test_fuzzy_match.py

@@ -0,0 +1,67 @@
+"""Tests for the fuzzy matching module."""
+
+from tools.fuzzy_match import fuzzy_find_and_replace
+
+
+class TestExactMatch:
+    def test_single_replacement(self):
+        content = "hello world"
+        new, count, err = fuzzy_find_and_replace(content, "hello", "hi")
+        assert err is None
+        assert count == 1
+        assert new == "hi world"
+
+    def test_no_match(self):
+        content = "hello world"
+        new, count, err = fuzzy_find_and_replace(content, "xyz", "abc")
+        assert count == 0
+        assert err is not None
+        assert new == content
+
+    def test_empty_old_string(self):
+        new, count, err = fuzzy_find_and_replace("abc", "", "x")
+        assert count == 0
+        assert err is not None
+
+    def test_identical_strings(self):
+        new, count, err = fuzzy_find_and_replace("abc", "abc", "abc")
+        assert count == 0
+        assert "identical" in err
+
+    def test_multiline_exact(self):
+        content = "line1\nline2\nline3"
+        new, count, err = fuzzy_find_and_replace(content, "line1\nline2", "replaced")
+        assert err is None
+        assert count == 1
+        assert new == "replaced\nline3"
+
+
+class TestWhitespaceDifference:
+    def test_extra_spaces_match(self):
+        content = "def  foo(  x,  y  ):"
+        new, count, err = fuzzy_find_and_replace(content, "def foo( x, y ):", "def bar(x, y):")
+        assert count == 1
+        assert "bar" in new
+
+
+class TestIndentDifference:
+    def test_different_indentation(self):
+        content = "    def foo():\n        pass"
+        new, count, err = fuzzy_find_and_replace(content, "def foo():\n    pass", "def bar():\n    return 1")
+        assert count == 1
+        assert "bar" in new
+
+
+class TestReplaceAll:
+    def test_multiple_matches_without_flag_errors(self):
+        content = "aaa bbb aaa"
+        new, count, err = fuzzy_find_and_replace(content, "aaa", "ccc", replace_all=False)
+        assert count == 0
+        assert "Found 2 matches" in err
+
+    def test_multiple_matches_with_flag(self):
+        content = "aaa bbb aaa"
+        new, count, err = fuzzy_find_and_replace(content, "aaa", "ccc", replace_all=True)
+        assert err is None
+        assert count == 2
+        assert new == "ccc bbb ccc"