refactor: Extract ENV_TEMP pattern to inject_env_vars_local (Modal)

Created inject_env_vars_local() function in shared/common.sh to eliminate
duplicate temporary file creation pattern. Converted 10 Modal scripts:
- aider, claude, amazonq, cline, codex
- gemini, goose, interpreter, nanoclaw, openclaw

Reduces ~10-15 lines per script to 3-4 lines.

Pattern before:
  ENV_TEMP=$(mktemp)
  trap 'rm -f "${ENV_TEMP}"' EXIT
  cat > "${ENV_TEMP}" << EOF
  # [spawn:env]
  export KEY=value
  EOF
  upload_file "${ENV_TEMP}" "/tmp/env_config"
  run_server "cat /tmp/env_config >> ~/.zshrc && rm /tmp/env_config"

Pattern after:
  inject_env_vars_local upload_file run_server \
      "KEY=value"

Special case: nanoclaw.sh has additional DOTENV_TEMP for agent-specific
.env file, which remains unchanged.

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

modal/goose.sh

@@ -1,4 +1,5 @@
 #!/bin/bash
+# shellcheck disable=SC2154
 set -eo pipefail
 
 # Source common functions - try local file first, fall back to remote
@@ -46,17 +47,9 @@ fi
 # 6. Inject environment variables into ~/.zshrc
 log_warn "Setting up environment variables..."
 
-ENV_TEMP=$(mktemp)
-trap 'rm -f "${ENV_TEMP}"' EXIT
-cat > "${ENV_TEMP}" << EOF
-
-# [spawn:env]
-export GOOSE_PROVIDER=openrouter
-export OPENROUTER_API_KEY="${OPENROUTER_API_KEY}"
-EOF
-
-upload_file "${ENV_TEMP}" "/tmp/env_config"
-run_server "cat /tmp/env_config >> ~/.zshrc && rm /tmp/env_config"
+inject_env_vars_local upload_file run_server \
+    "GOOSE_PROVIDER=openrouter" \
+    "OPENROUTER_API_KEY=${OPENROUTER_API_KEY}"
 
 echo ""
 log_info "Modal sandbox setup completed successfully!"