card: add repo card (layout, batches, citing, submitting)

README.md

@@ -0,0 +1,56 @@
+---
+pretty_name: "Calibench: Leaderboard Results"
+license: cc-by-4.0
+viewer: false        # record/registry JSONs are not tabular data — read them via the schema
+tags:
+  - calibration
+  - camera-calibration
+  - camera-imu-calibration
+  - visual-inertial
+  - benchmark
+  - leaderboard
+---
+
+# Calibench: Leaderboard Results
+
+Machine-readable backend of the
+[**Calibench leaderboard**](https://huggingface.co/spaces/calibench-vi/leaderboard) —
+one JSON record per *(tool, dataset, split)* evaluation, plus the calibration
+outputs they came from. Browse it on the Space; this repo is the data of record.
+
+## Layout
+
+```
+tracks.json                      # track registry: dataset rosters per (track, split),
+                                 #   metric config {primary, columns}, scoring tau_max
+datasets.json                    # dataset catalog: per-rig hardware, shutter, lens,
+                                 #   IMUs, board, source/license/cite
+schemas/result.schema.json       # record schema (v1.1)
+<Tool>/<batch>/<id>.json         # result records   (batch = evaluation run date)
+<Tool>/<batch>/<id>.output.json  # the calibration outputs (intrinsics, extrinsics,
+                                 #   time offsets) each record's calibration_ref points at
+```
+
+**Batches** group the records produced by one evaluation run (`YYYY-MM-DD`), so a
+leaderboard state traces to an exact run set and the same tool can be compared
+across time. The leaderboard ranks each tool's latest batch per dataset by
+default; its *Compare batches* toggle splits methods into `tool @ batch`.
+
+**Verification**: `verification.status` is `self_reported` until the Calibench
+CI re-runs the evaluation (in progress) — self-reported reprojection statistics
+are not directly comparable across tools (each reports its own statistic); the
+leaderboard flags such mixed rankings.
+
+## Citing a leaderboard state
+
+Cite the **commit hash** shown in the leaderboard status line (every view names
+the exact revision of this repo it was rendered from), plus the Calibench
+citation in
+[`calibench-vi/datasets`](https://huggingface.co/datasets/calibench-vi/datasets).
+
+## Adding results
+
+Open a PR to
+[`yangyulin/calibench-submissions`](https://github.com/yangyulin/calibench-submissions)
+with your calibration outputs; CI validates against the schema and publishes
+records here. Records (the numbers/metadata) are CC-BY-4.0.