fix: dnf support in setup-node + setup-aws, node label t3.medium

- setup-node: detect dnf (Amazon Linux) alongside apk/apt-get
- setup-aws: detect dnf for official installer
- node Spot bumped to t3.medium (4GB) — Docusaurus OOM'd on t3.small

setup-aws/action.yml

@@ -1,8 +1,9 @@
 # tinqs/ci/setup-aws — Tinqs Studio CI
 # Installs AWS CLI and optionally logs into ECR.
-# Detects Alpine (musl) vs Debian (glibc) and uses the right install method.
-# Credentials come from the runner environment (IAM task role on Fargate, instance
-# profile on EC2/Lightsail) — no explicit key configuration needed.
+# Detects Alpine (apk/pip), Debian (apt-get), and Amazon Linux/RHEL (dnf).
+# Skips install if AWS CLI is already present (pre-baked AMI).
+# Credentials come from the runner environment (IAM instance profile on EC2,
+# task role on Fargate) — no explicit key configuration needed.
 # Composite action — runs directly on the host.
 # Author: Ozan + Claude Code — 2026-05-22
 
@@ -35,9 +36,8 @@ runs:
             # Alpine — use pip (AWS CLI v2 binary needs glibc)
             apk add --no-cache python3 py3-pip
             pip3 install --break-system-packages awscli 2>/dev/null || pip3 install awscli
-          elif command -v apt-get &>/dev/null; then
-            # Debian/Ubuntu — use official installer
-            apt-get update && apt-get install -y unzip curl
+          elif command -v dnf &>/dev/null || command -v apt-get &>/dev/null; then
+            # Amazon Linux / Debian — official installer (glibc available)
             curl -fsSL https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip -o /tmp/awscli.zip
             unzip -q /tmp/awscli.zip -d /tmp/aws-install
             /tmp/aws-install/aws/install