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.

setup-hermes.sh

@@ -124,16 +124,7 @@ echo -e "${GREEN}✓${NC} Dependencies installed"
 # Submodules (terminal backend + RL training)
 # ============================================================================
 
-echo -e "${CYAN}→${NC} Installing submodules..."
-
-# mini-swe-agent (terminal tool backend)
-if [ -d "mini-swe-agent" ] && [ -f "mini-swe-agent/pyproject.toml" ]; then
-    $UV_CMD pip install -e "./mini-swe-agent" && \
-        echo -e "${GREEN}✓${NC} mini-swe-agent installed" || \
-        echo -e "${YELLOW}⚠${NC} mini-swe-agent install failed (Docker/Modal terminal backends may not work, local terminal is unaffected)"
-else
-    echo -e "${YELLOW}⚠${NC} mini-swe-agent not found (run: git submodule update --init --recursive)"
-fi
+echo -e "${CYAN}→${NC} Installing optional submodules..."
 
 # tinker-atropos (RL training backend)
 if [ -d "tinker-atropos" ] && [ -f "tinker-atropos/pyproject.toml" ]; then