rebrand: rename AutoCoder to AutoForge across entire codebase

Complete project rebrand from AutoCoder to AutoForge, touching 62 files
across Python backend, FastAPI server, React UI, documentation, config,
and CI/CD.

Key changes:
- Rename autocoder_paths.py -> autoforge_paths.py with backward-compat
  migration from .autocoder/ -> .autoforge/ directories
- Update registry.py to migrate ~/.autocoder/ -> ~/.autoforge/ global
  config directory with fallback support
- Update security.py with fallback reads from legacy .autocoder/ paths
- Rename .claude/commands and skills from gsd-to-autocoder-spec to
  gsd-to-autoforge-spec
- Update all Python modules: client, prompts, progress, agent,
  orchestrator, server routers and services
- Update React UI: package.json name, index.html title, localStorage
  keys, all documentation sections, component references
- Update start scripts (bat/sh/py), examples, and .env.example
- Update CLAUDE.md and README.md with new branding and paths
- Update test files for new .autoforge/ directory structure
- Transfer git remote from leonvanzyl/autocoder to
  AutoForgeAI/autoforge

Backward compatibility preserved: legacy .autocoder/ directories are
auto-detected and migrated on next agent start. Config fallback chain
checks both new and old paths.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

server/services/assistant_chat_session.py

@@ -64,7 +64,7 @@ def get_system_prompt(project_name: str, project_dir: Path) -> str:
     """Generate the system prompt for the assistant with project context."""
     # Try to load app_spec.txt for context
     app_spec_content = ""
-    from autocoder_paths import get_prompts_dir
+    from autoforge_paths import get_prompts_dir
     app_spec_path = get_prompts_dir(project_dir) / "app_spec.txt"
     if app_spec_path.exists():
         try:
@@ -224,7 +224,7 @@ class AssistantChatSession:
                 "allow": permissions_list,
             },
         }
-        from autocoder_paths import get_claude_assistant_settings_path
+        from autoforge_paths import get_claude_assistant_settings_path
         settings_file = get_claude_assistant_settings_path(self.project_dir)
         settings_file.parent.mkdir(parents=True, exist_ok=True)
         with open(settings_file, "w") as f: