test: make tests/ mirror the source tree; drop issue numbers from filenames

`scripts/run_tests.sh tests/<dir>/` is how a change gets its regression
coverage run, so a test filed under the wrong directory is a test nobody
runs when that code changes. Two kinds of drift had accumulated.

Parallel directories for one source package, folded into the mirror:
  tests/acp        -> tests/acp_adapter   (its __init__/conftest move with it)
  tests/cli        -> tests/hermes_cli    (prompt_toolkit fixture merged into
                                           hermes_cli/conftest.py)
  tests/run_agent  -> tests/agent         (backoff fixture becomes
                                           agent/conftest.py)
  tests/relay      -> tests/gateway/relay
  tests/state      -> tests/hermes_state

246 loose files at tests/ root, routed by the package they import/patch:
hermes_cli, hermes_state, agent, gateway, tools, plugins, tui_gateway, cron.
Installer and desktop-update script tests go to tests/scripts/{install,
desktop_update}/. 43 tests of root-level modules (batch_runner, utils,
hermes_constants, packaging) stay at the root.

Filenames drop their issue numbers (95 files: test_89315_x.py -> test_x.py);
the number stays in the module docstring where it has context.

Collisions: test_cli_skin_integration.py existed in both tests/ and tests/cli
with different subsets — merged into one (10 tests, all kept);
run_agent/test_pre_compress_memory_context.py -> agent/..._handoff.py;
tests/test_account_usage.py -> agent/test_account_usage_fetch.py;
tests/test_web_server.py -> hermes_cli/test_web_server_ws_ping.py.
Deleted: test_minisweagent_path.py (empty since PR #2804),
test_model_picker_scroll.py (tested a private copy of the logic, imported
nothing), test_process_loop_event_loop_warning.py (asserted asyncio behaviour,
imported nothing from Hermes).

Repo-root path arithmetic (Path(__file__).parents[N], dirname chains) is
bumped for the 202 files that changed depth and verified by evaluating every
such expression against the new location. classify_changes' desktop-updater
lane prefix, tests-os.yml's ignore glob and every in-tree path comment follow
the moves. tests/test_tests_tree_layout.py keeps the tree from drifting back.

tests/test_ws_keepalive_config.py

@@ -1,92 +0,0 @@
-"""Config propagation tests for the WS keepalive + orphan-reap grace knobs (#79635)."""
-
-import textwrap
-
-import pytest
-
-
-@pytest.fixture()
-def _temp_home(tmp_path, monkeypatch):
-    home = tmp_path / "hermes-home"
-    home.mkdir()
-    monkeypatch.setenv("HERMES_HOME", str(home))
-    monkeypatch.delenv("HERMES_TUI_WS_ORPHAN_REAP_GRACE_S", raising=False)
-    return home
-
-
-def _write_config(home, body: str) -> None:
-    (home / "config.yaml").write_text(textwrap.dedent(body))
-
-
-def test_dashboard_ws_defaults_present(_temp_home):
-    from hermes_cli.config import load_config
-
-    _write_config(_temp_home, "model:\n  default: test-model\n")
-    cfg = load_config()
-    dash = cfg.get("dashboard") or {}
-    assert dash.get("ws_ping_interval") == 20.0
-    assert dash.get("ws_ping_timeout") == 20.0
-    assert dash.get("ws_orphan_reap_grace_s") == 20.0
-
-
-def test_dashboard_ws_values_propagate_from_yaml(_temp_home):
-    from hermes_cli.config import load_config
-
-    _write_config(
-        _temp_home,
-        """
-        dashboard:
-          ws_ping_interval: 45.5
-          ws_ping_timeout: 10
-          ws_orphan_reap_grace_s: 90
-        """,
-    )
-    cfg = load_config()
-    dash = cfg["dashboard"]
-    assert dash["ws_ping_interval"] == 45.5
-    assert dash["ws_ping_timeout"] == 10
-    assert dash["ws_orphan_reap_grace_s"] == 90
-    # Deep-merge: sibling defaults survive a partial user section.
-    assert dash.get("theme") == "default"
-
-
-def test_ws_orphan_reap_grace_reads_config(_temp_home):
-    from tui_gateway import server
-
-    _write_config(
-        _temp_home,
-        """
-        dashboard:
-          ws_orphan_reap_grace_s: 33
-        """,
-    )
-    assert server._resolve_ws_orphan_reap_grace() == 33.0
-
-
-def test_ws_orphan_reap_grace_env_var_overrides_config(_temp_home, monkeypatch):
-    from tui_gateway import server
-
-    _write_config(
-        _temp_home,
-        """
-        dashboard:
-          ws_orphan_reap_grace_s: 33
-        """,
-    )
-    monkeypatch.setenv("HERMES_TUI_WS_ORPHAN_REAP_GRACE_S", "7")
-    assert server._resolve_ws_orphan_reap_grace() == 7.0
-
-
-def test_ws_orphan_reap_grace_invalid_values_fall_back(_temp_home, monkeypatch):
-    from tui_gateway import server
-
-    _write_config(
-        _temp_home,
-        """
-        dashboard:
-          ws_orphan_reap_grace_s: not-a-number
-        """,
-    )
-    assert server._resolve_ws_orphan_reap_grace() == 20.0
-    monkeypatch.setenv("HERMES_TUI_WS_ORPHAN_REAP_GRACE_S", "-5")
-    assert server._resolve_ws_orphan_reap_grace() == 0.0