Add inline controller remap modal and descriptor-based bindings

- Expand `Alt+C` from controller selection to config/remap UI with learn, clear, and reset flows
- Persist full controller binding descriptors through IPC/config (buttons, axes, directions, D-pad fallback)
- Update runtime/tests/docs/config examples for new binding schema; keep `Alt+Shift+C` debug modal

changes/controller-inline-remap.md

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+type: changed
+area: overlay
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+- Expanded the `Alt+C` controller modal into an inline config/remap flow with preferred-controller saving and per-action learn mode for buttons, triggers, and stick directions.