video-gen: prefer Seedance 2.0 on every gateway that supports it

Expands the Seedance 2.0 surface from fal.ai-only to every gateway the
OpenMontage toolset can reach, so users on Replicate / Runway /
Higgsfield automatically route cinematic briefs through Seedance 2.0
instead of the gateway's prior default.

- tools/video/seedance_replicate (new): REPLICATE_API_TOKEN adapter for
  bytedance/seedance-2.0 and bytedance/seedance-2.0-fast. Same provider
  family ("seedance"), quality_score=0.95, premium capability flags.
- tools/video/runway_video: add seedance_2.0 / seedance_2.0_fast to the
  model enum as the new default, flag native_audio + multi_shot +
  camera_direction + lip_sync in supports, point agent_skills at
  seedance-2-0 Layer 3 skill. Note Runway Unlimited/Enterprise + non-US
  gating in the model description.
- tools/video/higgsfield_video: same pattern. seedance_2.0 is now the
  default model. Cost estimates calibrated to Higgsfield credit pricing
  (~$0.50-$1.20 per 5s).
- tools/video/_shared: annotate HEYGEN_PROVIDERS seedance_pro/lite as
  Seedance 1.x (2.0 on HeyGen flows through Video Agent / Avatar Shots
  which need a separate wrapper — tracked as follow-up).
- .agents/skills/seedance-2-0: update provider matrix to show which
  gateways are wrapped (fal.ai, Replicate, Runway, Higgsfield) vs. which
  are still roadmap (HeyGen Video Agent, BytePlus, Freepik, aggregators).

The scoring engine already deduplicates by provider="seedance" so
whichever gateway the user has configured wins automatically. Agents
passing preferred_provider="seedance" to video_selector route to the
best available Seedance 2.0 path without naming a specific gateway.

.agents/skills/seedance-2-0/SKILL.md

@@ -14,7 +14,7 @@ metadata:
 
 # Seedance 2.0 (ByteDance)
 
-Seedance 2.0 is the ByteDance Seed team's unified multimodal video+audio model (released Feb 2026, globally available via partner APIs April 2026). It is currently the **preferred premium default** for cinematic, trailer, teaser, and motion-led work inside OpenMontage when a paid gateway is configured.
+Seedance 2.0 is the ByteDance Seed team's unified multimodal video+audio model (released Feb 2026, globally available via partner APIs April 2026). It is the **preferred premium default** for cinematic, trailer, teaser, and motion-led work inside OpenMontage whenever any supporting gateway is configured. OpenMontage wraps four gateways directly (`seedance_video` → fal.ai, `seedance_replicate` → Replicate, `runway_video` with `model="seedance_2.0"` → Runway, `higgsfield_video` with `model="seedance_2.0"` → Higgsfield); BytePlus / Freepik / HeyGen-Video-Agent wrappers are on the roadmap. The scoring engine deduplicates by `provider="seedance"` so whichever gateway the user has configured wins automatically — agents should pass `preferred_provider="seedance"` to `video_selector` (or let the scorer pick) rather than routing to a specific gateway by name.
 
 ## Why it is the OpenMontage premium default
 
@@ -34,16 +34,16 @@ Switch away only for a specific reason: strict budget (use the `fast` variant or
 
 ## Provider surfaces
 
-| Surface | Env | OpenMontage tool | Notes |
-|---|---|---|---|
-| **fal.ai** (primary) | `FAL_KEY` | `seedance_video` | Model IDs below. Supports T2V, I2V, reference-to-video; `standard` and `fast` variants. Default in OpenMontage. |
-| **HeyGen** | `HEYGEN_API_KEY` | `heygen_video` (Video Agent / Avatar Shots) | Only platform with consent-verified real-face use via Avatar Shots. The `seedance_pro` / `seedance_lite` legacy provider strings on HeyGen map to Seedance 1.x — 2.0 access flows through the Video Agent / Avatar Shots endpoints rather than a stable provider parameter. |
-| **Replicate** | `REPLICATE_API_TOKEN` | not wrapped | `bytedance/seedance-2.0`, `bytedance/seedance-2.0-fast` |
-| **Runway** | Runway credentials | not wrapped | Third-party model inside Runway, **Unlimited/Enterprise plans, non-US only** |
-| **BytePlus ModelArk / Volcengine** | BytePlus token | not wrapped | Direct from ByteDance. Pro ~$0.15 / 5 s, Lite ~$0.010/s. Token-based. |
-| **Freepik** | Freepik token | not wrapped | `POST /v1/ai/image-to-video/seedance-pro-1080p` for 1080p I2V |
-| **Higgsfield** | Higgsfield plan | not wrapped | Emphasis on character identity + long-form chaining |
-| **Pollo / PiAPI / Atlas Cloud / AIMLAPI** | various | not wrapped | Aggregators resell fal.ai or ByteDance endpoints |
+| Surface | Env | OpenMontage tool | Status | Notes |
+|---|---|---|---|---|
+| **fal.ai** (primary) | `FAL_KEY` | `seedance_video` | ✅ wrapped | Model IDs below. Supports T2V, I2V, reference-to-video; `standard` and `fast` variants. Default in OpenMontage. |
+| **Replicate** | `REPLICATE_API_TOKEN` | `seedance_replicate` | ✅ wrapped | `bytedance/seedance-2.0` + `bytedance/seedance-2.0-fast`. Standard Replicate prediction API. |
+| **Runway** | `RUNWAY_API_KEY` | `runway_video` (model: `seedance_2.0`) | ✅ wrapped | Third-party Seedance 2.0 model inside Runway. **Unlimited/Enterprise plans, non-US only**. Selected via `model` param. |
+| **Higgsfield** | `HIGGSFIELD_API_KEY` + `_SECRET` | `higgsfield_video` (model: `seedance_2.0`) | ✅ wrapped | Seedance 2.0 is the default model on this tool. Emphasis on character identity + long-form chaining. |
+| **HeyGen** | `HEYGEN_API_KEY` | `heygen_video` (1.x only) + TODO | ⚠️ 1.x only | The `seedance_pro` / `seedance_lite` workflow provider strings on HeyGen map to Seedance 1.x. 2.0 access flows through Video Agent / Avatar Shots endpoints — a separate `seedance_heygen` tool is on the roadmap. |
+| **BytePlus ModelArk / Volcengine** | BytePlus token | not wrapped | 🔜 roadmap | Direct from ByteDance. Pro ~$0.15 / 5 s, Lite ~$0.010/s. Token-based. |
+| **Freepik** | Freepik token | not wrapped | 🔜 roadmap | `POST /v1/ai/image-to-video/seedance-pro-1080p` for 1080p I2V |
+| **Pollo / PiAPI / Atlas Cloud / AIMLAPI** | various | not wrapped | 🔜 roadmap | Aggregators resell fal.ai or ByteDance endpoints |
 
 ### fal.ai model IDs (used by `seedance_video`)