fix: replace hardcoded ~/.hermes paths with get_hermes_home() for profile support

* feat: GPT tool-use steering + strip budget warnings from history

Two changes to improve tool reliability, especially for OpenAI GPT models:

1. GPT tool-use enforcement prompt: Adds GPT_TOOL_USE_GUIDANCE to the
   system prompt when the model name contains 'gpt' and tools are loaded.
   This addresses a known behavioral pattern where GPT models describe
   intended actions ('I will run the tests') instead of actually making
   tool calls. Inspired by similar steering in OpenCode (beast.txt) and
   Cline (GPT-5.1 variant).

2. Budget warning history stripping: Budget pressure warnings injected by
   _get_budget_warning() into tool results are now stripped when
   conversation history is replayed via run_conversation(). Previously,
   these turn-scoped signals persisted across turns, causing models to
   avoid tool calls in all subsequent messages after any turn that hit
   the 70-90% iteration threshold.

* fix: replace hardcoded ~/.hermes paths with get_hermes_home() for profile support

Prep for the upcoming profiles feature — each profile is a separate
HERMES_HOME directory, so all paths must respect the env var.

Fixes:
- gateway/platforms/matrix.py: Matrix E2EE store was hardcoded to
  ~/.hermes/matrix/store, ignoring HERMES_HOME. Now uses
  get_hermes_home() so each profile gets its own Matrix state.

- gateway/platforms/telegram.py: Two locations reading config.yaml via
  Path.home()/.hermes instead of get_hermes_home(). DM topic thread_id
  persistence and hot-reload would read the wrong config in a profile.

- tools/file_tools.py: Security path for hub index blocking was
  hardcoded to ~/.hermes, would miss the actual profile's hub cache.

- hermes_cli/gateway.py: Service naming now uses the profile name
  (hermes-gateway-coder) instead of a cryptic hash suffix. Extracted
  _profile_suffix() helper shared by systemd and launchd.

- hermes_cli/gateway.py: Launchd plist path and Label now scoped per
  profile (ai.hermes.gateway-coder.plist). Previously all profiles
  would collide on the same plist file on macOS.

- hermes_cli/gateway.py: Launchd plist now includes HERMES_HOME in
  EnvironmentVariables — was missing entirely, making custom
  HERMES_HOME broken on macOS launchd (pre-existing bug).

- All launchctl commands in gateway.py, main.py, status.py updated
  to use get_launchd_label() instead of hardcoded string.

Test fixes: DM topic tests now set HERMES_HOME env var alongside
Path.home() mock. Launchd test uses get_launchd_label() for expected
commands.

tests/gateway/test_dm_topics.py

@@ -10,6 +10,7 @@ Covers:
 """
 
 import asyncio
+import os
 import sys
 from pathlib import Path
 from types import SimpleNamespace
@@ -227,7 +228,8 @@ def test_persist_dm_topic_thread_id_writes_config(tmp_path):
 
     adapter = _make_adapter()
 
-    with patch.object(Path, "home", return_value=tmp_path):
+    with patch.object(Path, "home", return_value=tmp_path), \
+         patch.dict(os.environ, {"HERMES_HOME": str(tmp_path / ".hermes")}):
         adapter._persist_dm_topic_thread_id(111, "General", 999)
 
     with open(config_file) as f:
@@ -366,7 +368,8 @@ def test_get_dm_topic_info_hot_reloads_from_config(tmp_path):
     with open(config_file, "w") as f:
         yaml.dump(config_data, f)
 
-    with patch.object(Path, "home", return_value=tmp_path):
+    with patch.object(Path, "home", return_value=tmp_path), \
+         patch.dict(os.environ, {"HERMES_HOME": str(tmp_path / ".hermes")}):
         result = adapter._get_dm_topic_info("111", "555")
 
     assert result is not None