feat: controller/gamepad support (#350)

Adds `nesgamepad`, basically "diet-coke vimputti" for Nestri's microVM
needs here.

Comes with direct mapping for:
- Sony
  - DualShock 4 (v2), DualSense
- Microsoft
  - Xbox 360 pad, Xbox One S pad
- Nintendo
  - Pro Controller
- Generic pad for unknown controllers

---------

Co-authored-by: DatCaptainHorse <DatCaptainHorse@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

build/kernel/nestri.fragment

@@ -14,6 +14,20 @@
 # NTSYNC is a great improvement over fsync and esync approaches.
 CONFIG_NTSYNC=y
 
+# ── Controllers ──────────────────────────────────────────
+# A controller of a family the box can rebuild is made here as the device
+# itself, from the real one's descriptor, through uhid; hid-generic binds to
+# it and gives it a hidraw node. That node is what Proton reads a controller through
+# when it wants the device rather than a gamepad abstraction of it, and it is
+# the only way a game that parses a controller's own reports -- to tell a
+# DualShock from an Xbox pad, say, and show the right buttons -- can work.
+#
+# Two generic switches and no vendor drivers, on purpose: games read the
+# hidraw node, not whatever a vendor driver would have made of the device, so
+# no controller family needs a switch of its own. HID_GENERIC is already on.
+CONFIG_UHID=y
+CONFIG_HIDRAW=y
+
 # ── Timers ───────────────────────────────────────────────
 # The one that cost a day of silent audio. The guest has no sound hardware, so
 # PipeWire drives its whole graph off a timerfd at a 2.67ms cycle, which a