chore: fixture backlog for Phase A toy run + gitignore cleanup

- fixtures/phase-a-toy.json — scaffold source for `autoresearch start`
  Phase A live run: val_vol_r2 metric, daily EUR/USD, HEPA encoder toy
- .gitignore: add runs/ (ephemeral run dirs), metrics.json, embeddings.json,
  HEARTBEAT, STATUS.md, pyc/__pycache__/.pytest_cache, eval binary
- untrack metrics.json (was a stale committed sample, now gitignored)

Launch on koala:
  python scripts/autoresearch_start.py fixtures/phase-a-toy.json phase-a-toy
  op run -- env LITELLM_KEY="$LITELLM_KEY" \
    python loop.py --run-dir runs/phase-a-toy --iters 3

Closes the last gate on jepa-fx-risk#11 Phase A (code shipped v1.4.0;
live run pending).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -34,3 +34,20 @@ bin/
 
 # downloaded + processed market data (track via DVC/MinIO, #10 — not git)
 data/
+
+# autoresearch run dirs (ephemeral; each scaffold rebuilds from fixtures/)
+runs/
+
+# ephemeral experiment outputs (generated by train.py / loop.py)
+metrics.json
+embeddings.json
+HEARTBEAT
+STATUS.md
+
+# python caches
+__pycache__/
+*.pyc
+.pytest_cache/
+
+# built Go binaries
+eval

fixtures/phase-a-toy.json

@@ -0,0 +1,11 @@
+{
+  "strategic_question": "What is the highest-leverage path to a JEPA-based FX tail-risk system that beats a GARCH/EWMA baseline on out-of-sample VaR-breach calibration, given one GPU and a solo researcher?",
+  "nodes": [
+    {
+      "id": "phase-a-toy",
+      "status": "autoresearch-ready",
+      "question": "Improve the OOS linear-probe R² (val_vol_r2) of the HEPA encoder on EUR/USD daily realized vol. The encoder is a small causal transformer trained with VICReg. Vary one hyperparameter or architectural choice per iteration — model size, learning rate, window, patch length, depth, VICReg loss weights — to push val_vol_r2 as high as possible on the 2022-2023 OOS slice.",
+      "candidate_metric": "val_vol_r2"
+    }
+  ]
+}

metrics.json

@@ -1,14 +0,0 @@
-{
-  "val_vol_r2": 0.3641397896593044,
-  "phase1_r2": 0.3908407688140869,
-  "n_test": 11641,
-  "knobs": {
-    "WINDOW": 120,
-    "PATCH_LEN": 24,
-    "D_MODEL": 128,
-    "DEPTH": 2,
-    "ALPHA": 0.1,
-    "DELTA_T_MAX": 3,
-    "EPOCHS": 300
-  }
-}