feat(req-013): add portfolio-list-user-required requirement and batch

- Add REQ-013: Portfolio list filtered by user requirement with acceptance criteria
- Add DCY-003 discovery document for portfolio list user filtering
- Create BAT-003 batch with planning, design, implementation, and verification
- Enhance app/cli/commands/portfolio.py with user-based list filtering
- Add comprehensive tests for portfolio list CLI command with user filtering
- Update docs indices (discovery, srs, batches)
- Improve README with latest capability status

tests/test_cli.py

@@ -458,10 +458,14 @@ def _portfolio() -> Portfolio:
 
 
 def test_cli_list_renders_table() -> None:
-    repo = FakeRepo(_portfolio())
+    repo = FakeRepo()
+    user = repo.create_user("alice", permission="read")
+    p = _portfolio()
+    p.owner_user_id = user.id
+    repo._portfolio = p
     runner = build_runner(repo)
 
-    result = runner.invoke(runner.app, ["portfolio", "list"])
+    result = runner.invoke(runner.app, ["portfolio", "list", "--user", "alice"])
 
     assert result.exit_code == 0
     assert "005930:tv" in result.stdout
@@ -820,11 +824,15 @@ def test_cli_tag_add_and_list() -> None:
 
 
 def test_cli_list_supports_tag_filters() -> None:
-    repo = FakeRepo(_portfolio())
+    repo = FakeRepo()
+    user = repo.create_user("alice", permission="read")
+    p = _portfolio()
+    p.owner_user_id = user.id
+    repo._portfolio = p
     repo.add_tag("005930:tv", tag="grade:A")
     runner = build_runner(repo)
 
-    result = runner.invoke(runner.app, ["portfolio", "list", "--include-tag", "grade:A", "--match-mode", "AND"])
+    result = runner.invoke(runner.app, ["portfolio", "list", "--include-tag", "grade:A", "--match-mode", "AND", "--user", "alice"])
 
     assert result.exit_code == 0
     assert "005930:tv" in result.stdout
@@ -1166,3 +1174,59 @@ def test_cli_service_token_rotate_can_abort() -> None:
     token = repo.get_service_token_by_name("permanent")
     assert token is not None
     assert token.token_prefix == "pref"
+
+
+# ---------------------------------------------------------------------------
+# portfolio list --user (REQ-013)
+# ---------------------------------------------------------------------------
+
+def test_cli_portfolio_list_without_user_exits_error() -> None:
+    repo = FakeRepo()
+    runner = build_runner(repo)
+
+    result = runner.invoke(runner.app, ["portfolio", "list"])
+
+    assert result.exit_code == 1
+    assert "--user" in result.stdout
+
+
+def test_cli_portfolio_list_with_valid_user_filters_by_owner() -> None:
+    repo = FakeRepo()
+    alice = repo.create_user("alice", permission="read")
+    bob = repo.create_user("bob", permission="read")
+    alice_portfolio = _portfolio()
+    alice_portfolio.owner_user_id = alice.id
+    repo._portfolio = alice_portfolio
+    runner = build_runner(repo)
+
+    result_alice = runner.invoke(runner.app, ["portfolio", "list", "--user", "alice"])
+    result_bob = runner.invoke(runner.app, ["portfolio", "list", "--user", "bob"])
+
+    assert result_alice.exit_code == 0
+    assert "005930:tv" in result_alice.stdout
+    assert result_bob.exit_code == 0
+    assert "005930:tv" not in result_bob.stdout
+
+
+def test_cli_portfolio_list_with_unknown_user_exits_error() -> None:
+    repo = FakeRepo()
+    runner = build_runner(repo)
+
+    result = runner.invoke(runner.app, ["portfolio", "list", "--user", "nobody"])
+
+    assert result.exit_code == 1
+    assert "nobody" in result.stdout
+
+
+def test_cli_portfolio_list_in_memory_mode_filters_owner() -> None:
+    repo = FakeRepo()
+    user = repo.create_user("alice", permission="read")
+    p = _portfolio()
+    p.owner_user_id = user.id
+    repo._portfolio = p
+    runner = build_runner(repo)
+
+    result = runner.invoke(runner.app, ["portfolio", "list", "--user", "alice"])
+
+    assert result.exit_code == 0
+    assert "005930:tv" in result.stdout