refactor: remove mini-swe-agent dependency — inline Docker/Modal backends (#2804)

Drop the mini-swe-agent git submodule. All terminal backends now use
hermes-agent's own environment implementations directly.

Docker backend:
- Inline the `docker run -d` container startup (was 15 lines in
  minisweagent's DockerEnvironment). Our wrapper already handled
  execute(), cleanup(), security hardening, volumes, and resource limits.

Modal backend:
- Import swe-rex's ModalDeployment directly instead of going through
  minisweagent's 90-line passthrough wrapper.
- Bake the _AsyncWorker pattern (from environments/patches.py) directly
  into ModalEnvironment for Atropos compatibility without monkey-patching.

Cleanup:
- Remove minisweagent_path.py (submodule path resolution helper)
- Remove submodule init/install from install.sh and setup-hermes.sh
- Remove mini-swe-agent from .gitmodules
- environments/patches.py is now a no-op (kept for backward compat)
- terminal_tool.py no longer does sys.path hacking for minisweagent
- mini_swe_runner.py guards imports (optional, for RL training only)
- Update all affected tests to mock the new direct subprocess calls
- Update README.md, CONTRIBUTING.md

No functionality change — all Docker, Modal, local, SSH, Singularity,
and Daytona backends behave identically. 6093 tests pass.

tests/tools/test_terminal_tool_requirements.py

@@ -8,7 +8,7 @@ terminal_tool_module = importlib.import_module("tools.terminal_tool")
 
 
 class TestTerminalRequirements:
-    def test_local_backend_does_not_require_minisweagent_package(self, monkeypatch):
+    def test_local_backend_requirements(self, monkeypatch):
         monkeypatch.setattr(
             terminal_tool_module,
             "_get_env_config",