feat(render+templates): Remotion engine, 16 branded templates (incl. 3D), seconds pricing, coming-soon

Render engine
- Add Remotion (code-based) as a 2nd render engine alongside After Effects.
  node-agent dispatches on Job.Engine; RunRemotion maps bindings -> --props,
  renders native then ffmpeg-scales to the quality tier (aspect-preserving).
- content.projects.render_engine + render_remotion_comp (migration 32);
  render-svc claim resolves engine and routes (skips .aep for Remotion).
- Admin TemplatesAdmin gains an engine picker + Remotion composition id field.

Template pack (services/remotion)
- 16 branded, Persian (Vazirmatn), color- and text-editable templates, each in
  3 aspects (16:9 / 1:1 / 9:16): LogoMotion, Opener, InstaPromo, YouTubeIntro,
  Slideshow, HappyBirthday, SalePromo, QuoteCard, EventInvite, Countdown,
  GlitterReveal (editable logo image), NowruzGreeting (animated characters),
  and 4 cinematic 3D templates via @remotion/three (Hero3D, Nowruz3D,
  Birthday3D, Promo3D) with reflections + bloom/DOF/vignette.
- scripts/seed_remotion_templates.py seeds containers/projects/scenes/colors.

Pricing
- Rewrite /pricing to the seconds-based model (charge = length x resolution),
  data-driven from /v1/plans, Toman, broker checkout.

Coming-soon
- Persian experimental-build overlay on all pages (launch date + countdown).

Fixes
- middleware matcher bypasses all static asset paths; catalog mapping passes
  cover image + preview video so real thumbnails render.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

messages/en.json

@@ -144,14 +144,14 @@
     "a7": "Yes. Cancel from your account settings at any time. You keep access through the end of your billing period, and you can downgrade to Free without losing your projects."
   },
   "pricing": {
-    "heading": "Choose your FlatRender plan",
+    "heading": "Pay by the second, not by the video",
     "monthly": "Monthly",
     "annual": "Annual",
     "saveBadge": "Save up to {percent}%",
     "subscribe": "Subscribe",
     "freeBannerTitle": "Free plan",
     "freeBannerDesc": "Free forever, no credit card required",
-    "perMonth": "/ mo",
+    "perMonth": "monthly",
     "billedAnnually": "billed annually",
     "compareTitle": "Compare all plans",
     "allFeatures": "All features",
@@ -161,7 +161,45 @@
     "proName": "Pro",
     "proDesc": "Become a pro and unlock more powerful video, design and website editing tools for commercial use.",
     "businessName": "Business",
-    "businessDesc": "Advanced level solution for teams and businesses. Includes reseller license."
+    "businessDesc": "Advanced level solution for teams and businesses. Includes reseller license.",
+    "subheading": "Each render costs render-seconds equal to the video length × a quality multiplier. Every plan gives you a monthly bucket of render-seconds.",
+    "toman": "Toman",
+    "free": "Free",
+    "mostPopular": "Most popular",
+    "currentPlan": "Current plan",
+    "choosePlan": "Choose plan",
+    "startFree": "Start free",
+    "processing": "Redirecting…",
+    "signInToBuy": "Sign in to buy",
+    "emptyState": "No plans are available right now.",
+    "perMonthSuffix": "/ mo",
+    "featSeconds": "{seconds} render-seconds / month",
+    "featResolution": "Up to {res} quality",
+    "featParallelOne": "1 render at a time",
+    "featParallel": "{n} parallel renders",
+    "featStorage": "{gb} GB cloud storage",
+    "featSpeed": "{factor}× render speed",
+    "featWatermarkOn": "FlatRender watermark",
+    "featWatermarkOff": "No watermark",
+    "calcTitle": "How many seconds do I need?",
+    "calcDesc": "Pick a video length and quality to see the per-render cost in seconds.",
+    "calcLength": "Video length",
+    "calcResolution": "Output quality",
+    "calcCost": "Cost per render",
+    "calcSecondsUnit": "seconds",
+    "calcRendersWith": "With each plan:",
+    "calcVideosFmt": "≈ {count} videos",
+    "multiplierTitle": "Quality multiplier",
+    "multiplierDesc": "Render-seconds per render = video length × the multiplier below.",
+    "multiplierColRes": "Quality",
+    "multiplierColMul": "Multiplier",
+    "faqTitle": "Frequently asked",
+    "faqQ1": "What is a render-second?",
+    "faqA1": "Instead of a video-count limit, you buy render-seconds. A 15-second video at 720p uses exactly 15 seconds of your balance.",
+    "faqQ2": "Why does higher quality cost more seconds?",
+    "faqA2": "4K rendering is much heavier, so each second of video counts as 4 render-seconds; 1080p counts as 2×.",
+    "faqQ3": "What if I run out of seconds?",
+    "faqA3": "Upgrade your plan or wait for the next period. Your max resolution and parallel renders also follow your plan."
   },
   "footer": {
     "brandName": "FlatRender",