fix(security): remediate CVE-2026-42043 — upgrade axios ^1.14.0

- package.json: bump axios constraint from ^1.13.5 to ^1.14.0
- Dockerfile build stage: npm ci -> npm install so the semver range
  in package.json is honoured at build time (npm ci uses the lockfile
  exactly, bypassing the updated constraint)

frontend/Dockerfile

@@ -25,7 +25,7 @@ FROM node:20-alpine AS build
 WORKDIR /app
 
 COPY package*.json ./
-RUN npm ci
+RUN npm install
 
 COPY . .
 RUN npm run build