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_patch_parser.py

@@ -0,0 +1,139 @@
+"""Tests for the V4A patch format parser."""
+
+from tools.patch_parser import (
+    OperationType,
+    parse_v4a_patch,
+)
+
+
+class TestParseUpdateFile:
+    def test_basic_update(self):
+        patch = """\
+*** Begin Patch
+*** Update File: src/main.py
+@@ def greet @@
+ def greet():
+-    print("hello")
++    print("hi")
+*** End Patch"""
+        ops, err = parse_v4a_patch(patch)
+        assert err is None
+        assert len(ops) == 1
+
+        op = ops[0]
+        assert op.operation == OperationType.UPDATE
+        assert op.file_path == "src/main.py"
+        assert len(op.hunks) == 1
+
+        hunk = op.hunks[0]
+        assert hunk.context_hint == "def greet"
+        prefixes = [l.prefix for l in hunk.lines]
+        assert " " in prefixes
+        assert "-" in prefixes
+        assert "+" in prefixes
+
+    def test_multiple_hunks(self):
+        patch = """\
+*** Begin Patch
+*** Update File: f.py
+@@ first @@
+ a
+-b
++c
+@@ second @@
+ x
+-y
++z
+*** End Patch"""
+        ops, err = parse_v4a_patch(patch)
+        assert err is None
+        assert len(ops) == 1
+        assert len(ops[0].hunks) == 2
+        assert ops[0].hunks[0].context_hint == "first"
+        assert ops[0].hunks[1].context_hint == "second"
+
+
+class TestParseAddFile:
+    def test_add_file(self):
+        patch = """\
+*** Begin Patch
+*** Add File: new/module.py
++import os
++
++print("hello")
+*** End Patch"""
+        ops, err = parse_v4a_patch(patch)
+        assert err is None
+        assert len(ops) == 1
+
+        op = ops[0]
+        assert op.operation == OperationType.ADD
+        assert op.file_path == "new/module.py"
+        assert len(op.hunks) == 1
+
+        contents = [l.content for l in op.hunks[0].lines if l.prefix == "+"]
+        assert contents[0] == "import os"
+        assert contents[2] == 'print("hello")'
+
+
+class TestParseDeleteFile:
+    def test_delete_file(self):
+        patch = """\
+*** Begin Patch
+*** Delete File: old/stuff.py
+*** End Patch"""
+        ops, err = parse_v4a_patch(patch)
+        assert err is None
+        assert len(ops) == 1
+        assert ops[0].operation == OperationType.DELETE
+        assert ops[0].file_path == "old/stuff.py"
+
+
+class TestParseMoveFile:
+    def test_move_file(self):
+        patch = """\
+*** Begin Patch
+*** Move File: old/path.py -> new/path.py
+*** End Patch"""
+        ops, err = parse_v4a_patch(patch)
+        assert err is None
+        assert len(ops) == 1
+        assert ops[0].operation == OperationType.MOVE
+        assert ops[0].file_path == "old/path.py"
+        assert ops[0].new_path == "new/path.py"
+
+
+class TestParseInvalidPatch:
+    def test_empty_patch_returns_empty_ops(self):
+        ops, err = parse_v4a_patch("")
+        assert err is None
+        assert ops == []
+
+    def test_no_begin_marker_still_parses(self):
+        patch = """\
+*** Update File: f.py
+ line1
+-old
++new
+*** End Patch"""
+        ops, err = parse_v4a_patch(patch)
+        assert err is None
+        assert len(ops) == 1
+
+    def test_multiple_operations(self):
+        patch = """\
+*** Begin Patch
+*** Add File: a.py
++content_a
+*** Delete File: b.py
+*** Update File: c.py
+ keep
+-remove
++add
+*** End Patch"""
+        ops, err = parse_v4a_patch(patch)
+        assert err is None
+        assert len(ops) == 3
+        assert ops[0].operation == OperationType.ADD
+        assert ops[1].operation == OperationType.DELETE
+        assert ops[2].operation == OperationType.UPDATE