feat(infra): add Cloudflare fallback plan + self-hosted landing pages

Two infrastructure improvements for tech independence:

1. Cloudflare Fallback Documentation (docs/CLOUDFLARE_FALLBACK.md):
   - Plan B: WireGuard + Caddy on Hetzner VPS (€3.79/mo)
   - Complete Caddyfile with all 30+ subdomains
   - Step-by-step failover checklist (~15 min to switch)
   - Plan C: Direct IP with ISP

2. Self-Hosted Landing Pages (eliminates Cloudflare Pages dependency):
   - Nginx container (mana-infra-landings) on port 4400
   - Multi-site config: each subdomain → separate dist/ folder
   - Build script: scripts/mac-mini/build-landings.sh
   - Cloudflare Tunnel ingress rules for 10 landing page domains
   - Storage: /Volumes/ManaData/landings/ on external SSD
   - Domains: it, chats, pics, zitares, presis, clocks,
     manadeck, nutriphi, citycorners, docs

Migration path: Build landings locally, set Cloudflare DNS to
tunnel instead of Pages, then decommission CF Pages projects.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/mac-mini/build-landings.sh

@@ -0,0 +1,56 @@
+#!/bin/bash
+# Build all landing pages and copy dist/ to the shared nginx volume
+# Run on the Mac Mini after git pull
+#
+# Usage: ./scripts/mac-mini/build-landings.sh
+
+set -e
+
+PROJECT_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+OUTPUT_DIR="/Volumes/ManaData/landings"
+
+echo "=== Building Landing Pages ==="
+echo "Output: $OUTPUT_DIR"
+echo ""
+
+mkdir -p "$OUTPUT_DIR"
+
+# Landing pages to build (filter name → dist path → output name)
+declare -A LANDINGS=(
+    ["it"]="services/it-landing"
+    ["chat"]="apps/chat/apps/landing"
+    ["picture"]="apps/picture/apps/landing"
+    ["zitare"]="apps/zitare/apps/landing"
+    ["presi"]="apps/presi/apps/landing"
+    ["clock"]="apps/clock/apps/landing"
+    ["manadeck"]="apps/manadeck/apps/landing"
+    ["nutriphi"]="apps/nutriphi/apps/landing"
+    ["citycorners"]="apps/citycorners/apps/landing"
+)
+
+cd "$PROJECT_ROOT"
+
+for name in "${!LANDINGS[@]}"; do
+    dir="${LANDINGS[$name]}"
+    if [ -d "$dir" ]; then
+        echo "Building $name ($dir)..."
+        pnpm --filter "./$dir" build 2>&1 | tail -3
+
+        # Copy dist to output
+        if [ -d "$dir/dist" ]; then
+            rm -rf "$OUTPUT_DIR/$name"
+            cp -r "$dir/dist" "$OUTPUT_DIR/$name"
+            echo "  → $OUTPUT_DIR/$name ($(du -sh "$OUTPUT_DIR/$name" | cut -f1))"
+        else
+            echo "  ⚠ No dist/ found for $name"
+        fi
+    else
+        echo "  ⚠ Directory not found: $dir"
+    fi
+    echo ""
+done
+
+echo "=== Done ==="
+echo ""
+echo "Restart nginx to pick up changes:"
+echo "  docker restart mana-infra-landings"