Rename project to OBDash + per-metric colored multi-axis

Rename: the app is vehicle-agnostic, so 'ford-obd' was wrong. Rebranded all
code/docs/profile authors to OBDash; Gitea repo renamed justin/ford-obd ->
justin/obdash (remote + description updated). Ford the make and the
ford-6.0-powerstroke profile are unchanged (that vehicle really is a Ford).

Multi-axis upgrade (per request):
- MultiAxisPlot now gives each METRIC its own Y axis, each axis colored to
  match its line; the primary metric owns the LEFT axis, others stack right.
- Click a line to promote it to the left axis (sigClicked -> set_primary).
- Cleaner teardown (no removeItem warnings); axis label no longer doubles the
  unit; Normalize round-trips.

Validated headless: colored per-metric axes, promote-to-left, gauge view,
normalize toggle, profile switch; obdcore + diagnostics tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016yT89n4zR4qbrySoSiEyZs

run_gui.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-"""Launcher for the ford-obd GUI.
+"""Launcher for the OBDash GUI.
 
     pip install PySide6 pyqtgraph numpy pyserial
     python run_gui.py