fix(cloudflared): use --host 0.0.0.0 instead of --bind-addr for code-server

The --bind-addr flag caused code-server to fail entirely (app not
responding on any interface). The correct override for the
coder/code-server image is --host 0.0.0.0, which overrides the
entrypoint's --host 127.0.0.1.

Changes:
- Migration: Replace --bind-addr with --host 0.0.0.0, also handle
  existing broken templates by detecting --bind-addr and replacing it
- Runtime safety net: _ensure_web_bind_address uses --host 0.0.0.0
- Test fixture: Updated compose template to match

Quality gates: pytest 42 passed

apps/api/src/api/tool_instances.py

@@ -629,7 +629,7 @@ def _ensure_web_bind_address(compose_path: str, tool_type_name: str) -> None:
     from pathlib import Path
 
     KNOWN_BIND_FIXES = {
-        "code-server": "--bind-addr 0.0.0.0:8443",
+        "code-server": "--host 0.0.0.0",
         "jupyter-notebook": "start-notebook.sh --ip=0.0.0.0",
     }
 
@@ -669,9 +669,7 @@ def _ensure_web_bind_address(compose_path: str, tool_type_name: str) -> None:
             break
 
     compose_file.write_text(yaml.dump(compose_data, default_flow_style=False))
-    logger.info(
-        "Injected bind address for %s: %s", tool_type_name, bind_command
-    )
+    logger.info("Injected bind address for %s: %s", tool_type_name, bind_command)
 
 
 @router.post(