infra: replace gpt-oss with Ollama Pro + OpenCode Zen across hot paths

Ollama Pro plan went live today (39-model fleet on the same
OLLAMA_CLOUD_KEY) and OpenCode Zen was already wired in the gateway
but not consumed. Routing every gpt-oss call site to faster /
stronger replacements:

| Site | gpt-oss → replacement | Why |
|---|---|---|
| ollama_cloud default | gpt-oss:120b → deepseek-v3.2 | newest DeepSeek revision; live-probed `pong` |
| openrouter default | openai/gpt-oss-120b:free → x-ai/grok-4.1-fast | already the scrum LADDER's PRIMARY |
| modes.toml staffing_inference | openai/gpt-oss-120b:free → kimi-k2.6 | coding-specialized, on Ollama Pro |
| modes.toml doc_drift_check | gpt-oss:120b → gemini-3-flash-preview | speed leader for factual checks |
| scrum_master_pipeline tree-split MAP+REDUCE | gpt-oss:120b → gemini-3-flash-preview | latency-dominated path (5-20× per file) |
| bot/propose.ts CLOUD_MODEL | gpt-oss:120b → deepseek-v3.2 | same Ollama key, faster |
| mcp-server/observer.ts overseer label fallback | gpt-oss:120b → claude-opus-4-7 | matches new overseer model |
| crates/gateway/src/execution_loop overseer escalation | ollama_cloud/gpt-oss:120b → opencode/claude-opus-4-7 | frontier reasoning matters here — fires only after local self-correct fails twice; Zen pay-per-token cost is bounded |

Verification:
- `cargo check -p gateway --tests` — clean
- Live probes through localhost:3100/v1/chat:
  - `opencode/claude-opus-4-7` → "pong"
  - `gemini-3-flash-preview` (ollama_cloud) → "pong"
  - `kimi-k2.6` (ollama_cloud) → "pong"
  - `deepseek-v3.2` (ollama_cloud) → "Pong! 🏓"

Notes:
- kimi-k2:1t still upstream-broken (HTTP 500 on Ollama Pro probe today,
  matches yesterday's memory). Replacement table never picks it.
- The Rust changes need a `systemctl restart lakehouse.service` to
  take effect on the running gateway. TS callers reload on next run.
- aibridge/src/context.rs still has gpt-oss:{20b,120b} in its window-
  size lookup table; harmless and kept for callers that pass it
  explicitly as an override.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

config/providers.toml

@@ -27,10 +27,15 @@ name = "ollama_cloud"
 base_url = "https://ollama.com"
 auth = "bearer"
 auth_env = "OLLAMA_CLOUD_KEY"
-default_model = "gpt-oss:120b"
-# Cloud-tier Ollama. Key resolved from OLLAMA_CLOUD_KEY env at gateway
-# boot. Model-prefix routing: "cloud/<model>" auto-routes here
-# (see gateway::v1::resolve_provider).
+default_model = "deepseek-v3.2"
+# Cloud-tier Ollama (Pro plan as of 2026-04-28). Key resolved from
+# OLLAMA_CLOUD_KEY at gateway boot; Pro tier upgraded the account so
+# rate limits + model access widen without a key change. Model-prefix
+# routing: "cloud/<model>" auto-routes here. 39-model fleet now
+# includes deepseek-v3.2, deepseek-v4-{flash,pro}, gemini-3-flash-
+# preview, glm-{5,5.1}, kimi-k2.6, qwen3-coder-next.
+# 2026-04-28: default upgraded gpt-oss:120b → deepseek-v3.2 (newest
+# DeepSeek revision; kimi-k2:1t still upstream-broken with HTTP 500).
 
 [[provider]]
 name = "openrouter"
@@ -38,7 +43,7 @@ base_url = "https://openrouter.ai/api/v1"
 auth = "bearer"
 auth_env = "OPENROUTER_API_KEY"
 auth_fallback_files = ["/home/profit/.env", "/root/llm_team_config.json"]
-default_model = "openai/gpt-oss-120b:free"
+default_model = "x-ai/grok-4.1-fast"
 # Multi-provider gateway. Covers Anthropic, Google, OpenAI, MiniMax,
 # Qwen, Gemma, etc. Key resolved via crates/gateway/src/v1/openrouter.rs
 # resolve_openrouter_key() — env first, then fallback files.