Post-reorg cleanup: POSIX layer, and naming fixes

Follow-up to the monorepo re-org. Suite 35/35 plus host tests green.

POSIX compatibility is now its own library, library/posix/ (unistd, stdio),
layered strictly over the runtime — it calls the runtime's IPC/heap, never
system calls directly. The runtime is now POSIX-free (the danos-native
application ABI). The VFS wire protocol is danos-native throughout
(Stat -> FileStatus, .stat -> .status, O_CREAT -> create); the POSIX layer
maps the POSIX spellings at the boundary. The coding standard's ABI-name
exception is scoped to one place: a file is allowed POSIX spellings only if it
lives under library/posix/ — everywhere else, danos naming with no exception.

Naming fixes, all mechanical:
- initrd -> initial-ramdisk: the source file, the module, the tool
  (make-initial-ramdisk.py), the artifact (initial-ramdisk.img, including the
  bootloader's load path), and the identifiers.
- system/kernel/device-service.zig -> devices-broker.zig: it is ring-0 kernel
  code (the trusted device table + claim capability), not a ring-3 service. The
  future user-space device *manager* (policy) will live in system/services/.
- Dropped the daemon `d` suffix: hpetd -> hpet, busd -> bus. A driver lives in
  system/drivers/, so the folder already says what it is; encoding the role in
  the name too is redundant. The coding standard drops that exception.
- system/devices/aml/interp.zig -> interpreter.zig (the type was already
  Interpreter).

system/devices/aml/aml.zig

@@ -3,7 +3,7 @@
 //!
 //! This module has two stages. `parser.zig` walks the entire byte stream and
 //! records every named object into a namespace tree (`namespace.zig`), capturing
-//! method bodies and field/region layout. `interp.zig` then *evaluates* control
+//! method bodies and field/region layout. `interpreter.zig` then *evaluates* control
 //! methods on demand — running operators, control flow, and OperationRegion field
 //! access — so callers can resolve device status (`_STA`), current resource
 //! settings (`_CRS`), sleep states (`_Sx`), and the like against the live namespace.
@@ -17,10 +17,10 @@ pub const Node = @import("namespace.zig").Node;
 pub const NodeKind = @import("namespace.zig").NodeKind;
 
 /// The AML evaluator: interprets control methods (and reads Names/Fields) far
-/// enough for device discovery. See `interp.zig`.
-pub const Interpreter = @import("interp.zig").Interpreter;
-pub const Object = @import("interp.zig").Object;
-pub const EvaluateHal = @import("interp.zig").Hal;
+/// enough for device discovery. See `interpreter.zig`.
+pub const Interpreter = @import("interpreter.zig").Interpreter;
+pub const Object = @import("interpreter.zig").Object;
+pub const EvaluateHal = @import("interpreter.zig").Hal;
 
 /// The SLP_TYP values written to PM1a/PM1b control to enter a sleep state.
 pub const SleepType = struct {