scrum + applier + observer: switch to paid OpenRouter ladder, add Kimi K2.6 + Gemini 2.5

Ollama Cloud was throttled across all 6 cloud rungs in iters 1-9, which
forced the loop into 0-review iterations even though the architecture
was sound. Swapping to paid OpenRouter unblocks the test path.

Ladder changes (top-of-ladder paid models, all under $0.85/M either side):
- moonshotai/kimi-k2.6     ($0.74/$4.66, 256K) — capped at 25/hr
- x-ai/grok-4.1-fast       ($0.20/$0.50, 2M)   — primary general
- google/gemini-2.5-flash  ($0.30/$2.50, 1M)   — Google reasoning
- deepseek/deepseek-v4-flash ($0.14/$0.28, 1M) — cheap workhorse
- qwen/qwen3-235b-a22b-2507  ($0.07/$0.10, 262K) — cheapest big
Existing rungs (Ollama Cloud + free OR + local qwen3.5) kept as fallback.

Per-model rate limiter (MODEL_RATE_LIMITS in scrum_master_pipeline.ts):
- Persists call timestamps to data/_kb/rate_limit_calls.jsonl so caps
  survive process restarts (autonomous loop spawns a fresh subprocess
  per iteration; without persistence each iter would reset)
- O(1) writes, prune-on-read for the rolling 1h window
- Capped models log "SKIP (rate-limited: cap N/hr reached)" and the
  ladder cycles to the next rung
- J directive 2026-04-25: 25/hr on Kimi K2.6 to bound output cost

Observer hand-review cloud tier swapped from ollama_cloud/qwen3-coder:480b
to openrouter/x-ai/grok-4.1-fast — proven to emit precise semantic
verdicts (named "AccessControl::can_access() doesn't exist" specifically
in 2026-04-25 tests instead of the heuristic fallback).

Applier patch emitter swapped from ollama_cloud/qwen3-coder:480b to
openrouter/x-ai/grok-4.1-fast (default; LH_APPLIER_MODEL +
LH_APPLIER_PROVIDER override). This was the third LLM call we missed —
without it, observer accepts a review but applier never produces patches
because its emitter was still hitting the throttled account.

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

mcp-server/observer.ts

@@ -325,12 +325,17 @@ Respond ONLY with a JSON object:
 - reject: review invents APIs, fabricates calls, contradicts source. Do NOT record.
 - cycle: review is mediocre — partially grounded but wrong shape, try a stronger model.`;
 
+  // Hand-review uses paid OpenRouter so it sidesteps the Ollama Cloud
+  // throttle that drove every prior iter into the heuristic fallback.
+  // Grok 4.1 fast: $0.20 in / $0.50 out per M tokens, 2M ctx. A typical
+  // hand-review (~6K input + 300 output) costs ~$0.0014. Selected via
+  // J directive 2026-04-25 ("best model under $0.72/M").
   const resp = await fetch(`${LAKEHOUSE}/v1/chat`, {
     method: "POST",
     headers: { "Content-Type": "application/json" },
     body: JSON.stringify({
-      provider: "ollama_cloud",
-      model: "qwen3-coder:480b",
+      provider: "openrouter",
+      model: "x-ai/grok-4.1-fast",
       messages: [{ role: "user", content: prompt }],
       max_tokens: 300,
       temperature: 0.0,