chore: remove ~100 unused imports across 55 files (#3016)

Automated cleanup via pyflakes + autoflake with manual review.

Changes:
- Removed unused stdlib imports (os, sys, json, pathlib.Path, etc.)
- Removed unused typing imports (List, Dict, Any, Optional, Tuple, Set, etc.)
- Removed unused internal imports (hermes_cli.auth, hermes_cli.config, etc.)
- Fixed cli.py: removed 8 shadowed banner imports (imported from hermes_cli.banner
  then immediately redefined locally — only build_welcome_banner is actually used)
- Added noqa comments to imports that appear unused but serve a purpose:
  - Re-exports (gateway/session.py SessionResetPolicy, tools/terminal_tool.py
    is_interrupted/_interrupt_event)
  - SDK presence checks in try/except (daytona, fal_client, discord)
  - Test mock targets (auxiliary_client.py Path, mcp_config.py get_hermes_home)

Zero behavioral changes. Full test suite passes (6162/6162, 2 pre-existing
streaming test failures unrelated to this change).

hermes_cli/main.py

@@ -548,7 +548,6 @@ def cmd_gateway(args):
 
 def cmd_whatsapp(args):
     """Set up WhatsApp: choose mode, configure, install bridge, pair via QR."""
-    import os
     import subprocess
     from pathlib import Path
     from hermes_cli.config import get_env_value, save_env_value
@@ -742,12 +741,9 @@ def cmd_setup(args):
 def cmd_model(args):
     """Select default model — starts with provider selection, then model picker."""
     from hermes_cli.auth import (
-        resolve_provider, get_provider_auth_state, PROVIDER_REGISTRY,
-        _prompt_model_selection, _save_model_choice, _update_config_for_provider,
-        resolve_nous_runtime_credentials, fetch_nous_models, AuthError, format_auth_error,
-        _login_nous,
+        resolve_provider, AuthError, format_auth_error,
     )
-    from hermes_cli.config import load_config, save_config, get_env_value, save_env_value
+    from hermes_cli.config import load_config, get_env_value
 
     config = load_config()
     current_model = config.get("model")
@@ -1983,7 +1979,7 @@ def _model_flow_api_key_provider(config, provider_id, current_model=""):
     """Generic flow for API-key providers (z.ai, MiniMax)."""
     from hermes_cli.auth import (
         PROVIDER_REGISTRY, _prompt_model_selection, _save_model_choice,
-        _update_config_for_provider, deactivate_provider,
+        deactivate_provider,
     )
     from hermes_cli.config import get_env_value, save_env_value, load_config, save_config
 
@@ -2167,7 +2163,7 @@ def _model_flow_anthropic(config, current_model=""):
     import os
     from hermes_cli.auth import (
         PROVIDER_REGISTRY, _prompt_model_selection, _save_model_choice,
-        _update_config_for_provider, deactivate_provider,
+        deactivate_provider,
     )
     from hermes_cli.config import (
         get_env_value, save_env_value, load_config, save_config,