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_search_slow_query_log.py

@@ -1,60 +0,0 @@
-"""Tests for the session-search slow-query log (salvaged from PR #65544)."""
-
-import logging
-
-import pytest
-
-from hermes_state import SessionDB
-
-
-@pytest.fixture()
-def db(tmp_path):
-    d = SessionDB(db_path=tmp_path / "state.db")
-    d.create_session(session_id="s1", source="cli", model="m")
-    d.append_message("s1", role="user", content="hello graphiti 일본 MCP 정리")
-    yield d
-    d.close()
-
-
-def test_slow_log_emitted_at_zero_threshold(db, monkeypatch, caplog):
-    monkeypatch.setenv("HERMES_SEARCH_SLOW_MS", "0")
-    with caplog.at_level(logging.INFO, logger="hermes_state"):
-        rows = db.search_messages("graphiti", limit=5)
-    assert rows
-    slow = [r for r in caplog.records if "slow session search" in r.getMessage()]
-    assert slow, "threshold 0 must log every search"
-    msg = slow[0].getMessage()
-    assert "path=" in msg and "rows=1" in msg
-
-
-def test_no_log_under_threshold(db, monkeypatch, caplog):
-    monkeypatch.setenv("HERMES_SEARCH_SLOW_MS", "60000")
-    with caplog.at_level(logging.INFO, logger="hermes_state"):
-        db.search_messages("graphiti", limit=5)
-    assert not [r for r in caplog.records if "slow session search" in r.getMessage()]
-
-
-def test_path_attribution(db):
-    # Without the cjk tokenizer loaded, routing matches the pre-cjk shape.
-    assert db._describe_search_path("graphiti OR neo4j") == "fts5"
-    assert db._describe_search_path("우선순위 캘린더") == "trigram"
-    assert db._describe_search_path("일본 MCP") == "like_scan"
-
-
-def test_path_attribution_cjk_available(db):
-    # With the bigram index available, CJK queries (including 2-char terms)
-    # route to fts_cjk; lone 1-char CJK runs keep the LIKE route.
-    db._fts_cjk_available = True
-    try:
-        assert db._describe_search_path("일본 MCP") == "fts_cjk"
-        assert db._describe_search_path("우선순위 캘린더") == "fts_cjk"
-        assert db._describe_search_path("가 alone") == "like_scan"
-        assert db._describe_search_path("graphiti OR neo4j") == "fts5"
-    finally:
-        db._fts_cjk_available = False
-
-
-def test_results_unchanged_by_wrapper(db, monkeypatch):
-    monkeypatch.setenv("HERMES_SEARCH_SLOW_MS", "0")
-    rows = db.search_messages("graphiti", limit=5)
-    assert rows and rows[0]["session_id"] == "s1"