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>

env_constants.py

@@ -7,7 +7,7 @@ subprocesses.  Imported by both ``client.py`` (agent sessions) and
 ``server/services/chat_constants.py`` (chat sessions) to avoid maintaining
 duplicate lists.
 
-These allow autocoder to use alternative API endpoints (Ollama, GLM,
+These allow autoforge to use alternative API endpoints (Ollama, GLM,
 Vertex AI) without affecting the user's global Claude Code settings.
 """