refactor: replace inline HERMES_HOME re-implementations with get_hermes_home()

16 callsites across 14 files were re-deriving the hermes home path
via os.environ.get('HERMES_HOME', ...) instead of using the canonical
get_hermes_home() from hermes_constants. This breaks profiles — each
profile has its own HERMES_HOME, and the inline fallback defaults to
~/.hermes regardless.

Fixed by importing and calling get_hermes_home() at each site. For
files already inside the hermes process (agent/, hermes_cli/, tools/,
gateway/, plugins/), this is always safe. Files that run outside the
process context (mcp_serve.py, mcp_oauth.py) already had correct
try/except ImportError fallbacks and were left alone.

Skipped: hermes_constants.py (IS the implementation), env_loader.py
(bootstrap), profiles.py (intentionally manipulates the env var),
standalone scripts (optional-skills/, skills/), and tests.

hermes_cli/memory_setup.py

@@ -12,6 +12,8 @@ import os
 import sys
 from pathlib import Path
 
+from hermes_constants import get_hermes_home
+
 
 # ---------------------------------------------------------------------------
 # Curses-based interactive picker (same pattern as hermes tools)
@@ -275,7 +277,7 @@ def cmd_setup_provider(provider_name: str) -> None:
         config["memory"] = {}
 
     if hasattr(provider, "post_setup"):
-        hermes_home = str(Path(os.environ.get("HERMES_HOME", os.path.expanduser("~/.hermes"))))
+        hermes_home = str(get_hermes_home())
         provider.post_setup(hermes_home, config)
         return
 
@@ -326,7 +328,7 @@ def cmd_setup(args) -> None:
     # If the provider has a post_setup hook, delegate entirely to it.
     # The hook handles its own config, connection test, and activation.
     if hasattr(provider, "post_setup"):
-        hermes_home = str(Path(os.environ.get("HERMES_HOME", os.path.expanduser("~/.hermes"))))
+        hermes_home = str(get_hermes_home())
         provider.post_setup(hermes_home, config)
         return
 
@@ -336,7 +338,7 @@ def cmd_setup(args) -> None:
     if not isinstance(provider_config, dict):
         provider_config = {}
 
-    env_path = Path(os.environ.get("HERMES_HOME", os.path.expanduser("~/.hermes"))) / ".env"
+    env_path = get_hermes_home() / ".env"
     env_writes = {}
 
     if schema:
@@ -400,7 +402,7 @@ def cmd_setup(args) -> None:
     save_config(config)
 
     # Write non-secret config to provider's native location
-    hermes_home = str(Path(os.environ.get("HERMES_HOME", os.path.expanduser("~/.hermes"))))
+    hermes_home = str(get_hermes_home())
     if provider_config and hasattr(provider, "save_config"):
         try:
             provider.save_config(provider_config, hermes_home)