device-manager: data-driven driver matching via /etc/devices.csv

Replace the three hardcoded switch tables (pciDriverForIdentity, hidDriverFor,
usbDriverForIdentity) with an authoritative, human-readable device registry the
manager reads at boot. Matching is most-specific-wins across
base/subclass/prog_if/vendor/device/subsystem/hid, so a precise vendor:device
rule and a generic class rule coexist; an unmatched device is logged, never
guessed. This resolves docs' "matching stays code until the third bus".

- ABI: child_added and DeviceDescriptor gain vendor/device/subsystem; child_added
  gains a bus discriminator (BusKind) so PCI and USB class triples match against
  the right namespace.
- pci-bus reads vendor/device (config 0x00) and subsystem (0x2C, type-0) and
  reports them.
- library/device/registry: freestanding CSV parser + matchDriver() with
  specificity scoring; 5 unit tests wired into `zig build test`.
- etc/devices.csv bundled into the initrd; the kernel serves /etc directly, so
  the manager reads it before any filesystem service is up (fat starts later).
- virtio-gpu: drop the now-redundant post-spawn 1AF4:1050 re-confirm, since the
  registry binds this driver by exact identity.
- Remove the orphaned system/drivers/display driver (unreferenced by build or
  registry).
- docs: new devices-csv.md; device-manager.md "matching stays code" resolved.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KJqSiLLchDUUCoXn5jsiwd

system/services/acpi/acpi.zig

@@ -220,7 +220,7 @@ fn onInit(endpoint: ipc.Handle) bool {
         else
             std.log.info("reported {s} (device {d}, {d} resources)", .{ hid, entry.device_id, entry.resource_count });
         if (manager) |h| {
-            var report = device_manager_protocol.ChildAdded{ .parent = node_id, .bus_address = entry.device_id, .identity = 0, .device_id = entry.device_id };
+            var report = device_manager_protocol.ChildAdded{ .bus = @intFromEnum(device_manager_protocol.BusKind.acpi), .parent = node_id, .bus_address = entry.device_id, .identity = 0, .device_id = entry.device_id };
             @memcpy(report.hid[0..entry.hid_len], entry.hid[0..entry.hid_len]);
             var reply: [device_manager_protocol.message_maximum]u8 = undefined;
             _ = ipc.call(h, std.mem.asBytes(&report), &reply) catch {};