feat(remotion): Instagram channel-promo template + taste system + design-quality kit

The reference-round workflow, run end to end for a real template:

Taste system (how we learn the user's taste, persisted):
- references/TASTE_PROFILE.md (living design contract) + references/README.md (the
  daily loop) + a "reference round" stage in docs/TEMPLATE_BRIEF.md (provide refs or
  I suggest+mock directions).

Design-quality before/after:
- HeroDemo — the fix recipe vs the faint default: layered-depth background, a proper
  big video type scale, and a bold composed focal object. (Backgrounds were naked,
  text too small, scenes had no objects.)
- YaldaSofreh3D + IGPromoDirections + IGProfileMock — reference-match proofs
  (low-poly 3D, 3 IG-promo style directions, the realistic IG-light page).

Instagram channel-promo template (the deliverable — a flexible 5-scene FlexStory):
- igkit + 5 blocks: IGIntro, IGProfile (realistic IG-light profile, scales to all
  aspects), IGFeed (post grid), IGStats (animated count-up), IGFollowCTA (Follow taps
  to "Following").
- FlexStory gains a `finish` toggle so the IG-light scenes render clean (no brand
  grade). INSTAGRAM_PROMO preset + 3 aspect comps in Root.

Verified: a still of every scene at 9:16 renders clean; full preview MP4 rendering.

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

services/remotion/docs/TEMPLATE_BRIEF.md

@@ -52,6 +52,32 @@ Each round ≈ one `AskUserQuestion` call (≤4 questions), mostly multiple-choi
 
 ---
 
+## The reference round — lock the look (runs with Round 2)
+
+Before **any** building, lock the art direction against real visuals. Two modes, used together:
+
+- **You provide** — I ask: *"Got references for this? Paste them (+ one line of why)."* I extract
+  the DNA into [`references/TASTE_PROFILE.md`](../references/TASTE_PROFILE.md), so the build
+  inherits *your* taste, not my defaults.
+- **I suggest** — for the chosen type I propose **2–4 named style directions** AND **mock each up
+  as a cheap still / SVG** (no external images needed), so you pick from real visuals — not words.
+  I can also **web-search** live examples / asset packs / current trends and **link** them for you
+  to open and react to.
+
+**Output:** a locked **direction** (style + palette + motifs + reference notes) written into the
+Spec's `art` block and appended to the taste board. Then the gate continues: build → **cheap
+still → you approve** → full render.
+
+**Honest constraints:**
+- I can web-search and *link* real references, but rendering arbitrary external images inline is
+  unreliable from this environment — so the dependable "suggest" engine is **me mocking the
+  directions myself** (as today's storyboards/characters were). Web search supplements, doesn't
+  replace it.
+- **Footage:** I suggest CC0 sources + search/link, but footage is **vendored-CC0** (manual fetch)
+  or the **editable-backdrop** architecture — we can't AI-generate it (no GPU). Flag this per brief.
+
+---
+
 ## Template Spec (the output)
 
 The Q&A produces this structure, saved to `services/remotion/briefs/<slug>.md`: