refactor: remove 24 confirmed dead functions — 432 lines of unused code

Each function was verified to have exactly 1 reference in the entire
codebase (its own definition). Zero calls, zero imports, zero string
references anywhere including tests.

Removed by category:

Superseded wrappers (replaced by newer implementations):
- agent/anthropic_adapter.py: run_hermes_oauth_login, refresh_hermes_oauth_token
- hermes_cli/callbacks.py: sudo_password_callback (superseded by CLI method)
- hermes_cli/setup.py: _set_model_provider, _sync_model_from_disk
- tools/file_tools.py: get_file_tools (superseded by registry.register)
- tools/cronjob_tools.py: get_cronjob_tool_definitions (same)
- tools/terminal_tool.py: _check_dangerous_command (_check_all_guards used)

Dead private helpers (lost their callers during refactors):
- agent/anthropic_adapter.py: _convert_user_content_part_to_anthropic
- agent/display.py: honcho_session_line, write_tty
- hermes_cli/providers.py: _build_labels (+ dead _labels_cache var)
- hermes_cli/tools_config.py: _prompt_yes_no
- hermes_cli/models.py: _extract_model_ids
- hermes_cli/uninstall.py: log_error
- gateway/platforms/feishu.py: _is_loop_ready
- tools/file_operations.py: _read_image (64-line method)
- tools/process_registry.py: cleanup_expired
- tools/skill_manager_tool.py: check_skill_manage_requirements

Dead class methods (zero callers):
- run_agent.py: _is_anthropic_url (logic duplicated inline at L618)
- run_agent.py: _classify_empty_content_response (68-line method, never wired)
- cli.py: reset_conversation (callers all use new_session directly)
- cli.py: _clear_current_input (added but never wired in)

Other:
- gateway/delivery.py: build_delivery_context_for_tool
- tools/browser_tool.py: get_active_browser_sessions

cli.py

@@ -3536,13 +3536,6 @@ class HermesCLI:
         _cprint(f"  Original session: {parent_session_id}")
         _cprint(f"  Branch session:   {new_session_id}")
 
-    def reset_conversation(self):
-        """Reset the conversation by starting a new session."""
-        # Shut down memory provider before resetting — actual session boundary
-        if hasattr(self, 'agent') and self.agent:
-            self.agent.shutdown_memory_provider(self.conversation_history)
-        self.new_session()
-    
     def save_conversation(self):
         """Save the current conversation to a file."""
         if not self.conversation_history:
@@ -6290,14 +6283,6 @@ class HermesCLI:
             except Exception:
                 pass
 
-    def _clear_current_input(self) -> None:
-        if getattr(self, "_app", None):
-            try:
-                self._app.current_buffer.text = ""
-            except Exception:
-                pass
-
-
     def chat(self, message, images: list = None) -> Optional[str]:
         """
         Send a message to the agent and get a response.