feat: implement camera capture step

Add in-app camera capture to the upload flow. Guests can now take photos
and record videos directly via getUserMedia without leaving the app.
The captured media is immediately queued through the existing IndexedDB
upload pipeline alongside library-picked files.

- CameraCapture.svelte: fullscreen overlay with live preview, photo
  capture (JPEG via canvas), video recording (WebM/MP4 via MediaRecorder),
  front/back camera toggle, recording timer, and permission-denied error state
- Upload page: side-by-side "Gallery" and "Camera" pickers; shared
  caption/hashtags fields apply to both sources; Blob→File conversion
  with timestamped filename before enqueue
- .env.test: reference environment config for local testing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.env.test

@@ -0,0 +1,45 @@
+# ── Domain ────────────────────────────────────────────────────────────────────
+# Public domain Caddy will serve and obtain a TLS certificate for.
+DOMAIN=my-event.example.com
+
+# ── App server ────────────────────────────────────────────────────────────────
+APP_PORT=3000
+
+# ── Database ──────────────────────────────────────────────────────────────────
+DATABASE_URL=postgres://eventsnap:secret@db:5432/eventsnap
+POSTGRES_USER=eventsnap
+POSTGRES_PASSWORD=secret
+POSTGRES_DB=eventsnap
+
+# ── Authentication ────────────────────────────────────────────────────────────
+# Generate with: openssl rand -hex 64
+JWT_SECRET=change_me_to_a_random_64_byte_hex_string
+SESSION_EXPIRY_DAYS=30
+
+# Admin dashboard password (bcrypt hash).
+# Generate with: htpasswd -bnBC 12 "" yourpassword | tr -d ':\n'
+ADMIN_PASSWORD_HASH=$2y$12$placeholder_replace_me
+
+# ── Event ─────────────────────────────────────────────────────────────────────
+EVENT_NAME=Max & Maria's Wedding
+EVENT_SLUG=max-maria-2026
+
+# ── Storage ───────────────────────────────────────────────────────────────────
+MEDIA_PATH=/media
+
+# ── Upload limits ─────────────────────────────────────────────────────────────
+DEFAULT_MAX_IMAGE_SIZE_MB=20
+DEFAULT_MAX_VIDEO_SIZE_MB=500
+
+# ── Rate limiting ─────────────────────────────────────────────────────────────
+DEFAULT_UPLOAD_RATE_PER_HOUR=10
+DEFAULT_FEED_RATE_PER_MIN=60
+DEFAULT_EXPORT_RATE_PER_DAY=3
+
+# ── Capacity ──────────────────────────────────────────────────────────────────
+DEFAULT_ESTIMATED_GUEST_COUNT=100
+# Fraction of total storage that triggers the "low storage" warning (0.0–1.0)
+DEFAULT_QUOTA_TOLERANCE=0.75
+
+# ── Workers ───────────────────────────────────────────────────────────────────
+COMPRESSION_WORKER_CONCURRENCY=2