Add READMEs for the repo and every generation, root CLAUDE.md and .gitattributes

The root README has the timeline of all generations since 2009. Each generation folder explains its hardware and what is in it. .gitattributes turns off line-ending conversion so all files stay as they were.

original-frame/README.md

@@ -0,0 +1,12 @@
+# Original frame (2009–2023)
+
+The mechanical design every version up to 2023 was built on. The 2026 robot has a new design, see
+`../2026-current/hardware/fusion360/`.
+
+| File | Date | What |
+|---|---|---|
+| `poot.dxf` | 2009-10 | leg ("poot") |
+| `hexapod been.dxf` | 2009-12 | leg ("been") |
+| `poot2.dwg` | 2011-04 | leg, second version |
+| `body.dxf`, `Body.jpg` | 2011-07 | body plate, for the Arduino Mega + SSC-32 rebuild |
+| `bracket.dxf` | 2011-07 | servo bracket |