build: the unix paths retire — configuration, logs, and volumes move into the danos tree

/etc/init.csv and /etc/devices.csv become /system/configuration/*.csv (the
repo's etc/ moves to system/configuration/, mirroring the runtime tree),
/var/log becomes /system/logs, and /mnt/usb becomes /volumes/usb. The
kernel VFS gains a carve-out so FAT may serve exactly /system/configuration
and /system/logs beneath the initrd-backed /system while /system and /test
themselves stay unshadowable; FAT's single /var mount splits into those two
rewritten mounts. The kvfs readdir check learns /system's third child and
the ramdisk spawn sweep skips the configuration tree.

Suite 106/106.

library/csv/build.zig

@@ -1,5 +1,5 @@
 //! The "csv" library domain: shared CSV helpers (comment stripping, field
-//! iteration) for the /etc/*.csv config files — the device registry and the
+//! iteration) for the /system/configuration/*.csv config files — the device registry and the
 //! init service list both parse them.
 
 const std = @import("std");

library/csv/csv.zig

@@ -1,5 +1,5 @@
-//! Minimal CSV helpers shared by the `/etc/*.csv` config files — the device
-//! registry (`/etc/devices.csv`) and the init service list (`/etc/init.csv`).
+//! Minimal CSV helpers shared by the `/system/configuration/*.csv` config files — the device
+//! registry (`/system/configuration/devices.csv`) and the init service list (`/system/configuration/init.csv`).
 //! Freestanding, no allocator: returned fields are slices into the source line,
 //! so the source must outlive them. `#` starts a comment (whole-line or trailing);
 //! whitespace around a field is trimmed, so columns may be padded for alignment.

library/device/build.zig

@@ -97,7 +97,7 @@ pub fn build(b: *std.Build) void {
             .{ .name = "block-protocol", .module = protocol.module("block-protocol") },
         },
     });
-    // The device registry: parse /etc/devices.csv into match rules and bind a
+    // The device registry: parse /system/configuration/devices.csv into match rules and bind a
     // reported device to a driver. Pure logic (no hardware, no syscalls), so it
     // unit-tests on the host; the device manager imports it.
     _ = b.addModule("device-registry", .{

library/device/build.zig.zon

@@ -8,7 +8,7 @@
         .kernel = .{ .path = "../kernel" },
         // driver speaks device-manager-protocol; block/usb their transfer protocols.
         .protocol = .{ .path = "../protocol" },
-        // device-registry parses /etc/devices.csv with the shared csv helpers.
+        // device-registry parses /system/configuration/devices.csv with the shared csv helpers.
         .csv = .{ .path = "../csv" },
     },
     .paths = .{""},

library/device/model/device-abi.zig

@@ -126,7 +126,7 @@ pub const DeviceDescriptor = extern struct {
     // names with the pci-class module.
     pci_class: u64,
     // Numeric identity beyond the class triple, mirrored in the bus report's
-    // ChildAdded so /etc/devices.csv can bind on it: `vendor`/`device` are the PCI
+    // ChildAdded so /system/configuration/devices.csv can bind on it: `vendor`/`device` are the PCI
     // vendor/device (or USB idVendor/idProduct), `subsystem` is the PCI subsystem id
     // packed `(subsystem_vendor << 16) | subsystem_device`. Zero where the bus has no
     // such concept. Defaulted so existing descriptor literals keep compiling and lay

library/device/registry/device-registry.zig

@@ -1,4 +1,4 @@
-//! The device registry: parse `/etc/devices.csv` into match rules and bind a
+//! The device registry: parse `/system/configuration/devices.csv` into match rules and bind a
 //! reported device to a driver. This is the data-driven replacement for the
 //! device manager's three hand-written `switch` tables (`pciDriverForIdentity`,
 //! `hidDriverFor`, `usbDriverForIdentity`); the registry is now **authoritative**
@@ -11,7 +11,7 @@
 //! That keeps this module freestanding and unit-testable with plain `zig test`.
 //!
 //! The file format (docs/device-driver-development/device-manager.md, and the
-//! `/etc/devices.csv` header itself): one rule per line, nine comma-separated
+//! `/system/configuration/devices.csv` header itself): one rule per line, nine comma-separated
 //! fields, `#` starts a comment (whole-line or trailing), blank lines ignored.
 //!
 //!     bus, base, class, prog_if, vendor, device, subsystem, hid, driver
@@ -226,7 +226,7 @@ fn parseLine(line: []const u8) Line {
     } };
 }
 
-/// Parse a whole `/etc/devices.csv` into `out_rules`. The string fields of the
+/// Parse a whole `/system/configuration/devices.csv` into `out_rules`. The string fields of the
 /// returned rules point into `source`, which must outlive them.
 pub fn parse(source: []const u8, out_rules: []Rule) ParseResult {
     var result: ParseResult = .{ .count = 0, .malformed = 0, .truncated = false };

library/kernel/file-system.zig

@@ -305,7 +305,7 @@ pub fn makePath(path: []const u8) bool {
         while (end < path.len and path[end] != '/') end += 1;
         const prefix = path[0..end];
         if (prefix.len == 0 or (prefix.len == 1 and prefix[0] == '/')) continue;
-        // Best-effort per prefix: components at or above a mount point ("/mnt")
+        // Best-effort per prefix: components at or above a mount point ("/volumes")
         // are router names, not filesystem nodes — they neither exist as nodes
         // nor accept mkdir, and that is fine. Only the final verdict counts.
         if (!exists(prefix)) _ = makeDirectory(prefix);
@@ -348,8 +348,9 @@ pub fn mount(target: []const u8, backend: ipc.Handle) bool {
 }
 
 /// As `mount`, with a backend-side rewrite prefix: a path under `target` reaches
-/// the backend as `rewrite` + the mount-relative tail. How one volume serves two
-/// mounts ("/mnt/usb" from its root, "/var" from its /var subtree).
+/// the backend as `rewrite` + the mount-relative tail. How one volume serves
+/// several mounts ("/volumes/usb" from its root, "/system/logs" from its
+/// /system/logs subtree).
 pub fn mountRewritten(target: []const u8, backend: ipc.Handle, rewrite: []const u8) bool {
     return fsMount(target, backend, rewrite);
 }

library/protocol/device-manager/device-manager-protocol.zig

@@ -12,7 +12,7 @@
 pub const version: u16 = 1;
 
 /// Which bus a `child_added` came from — stated by the reporting bus driver so
-/// the manager's /etc/devices.csv matcher knows how to read the report's identity
+/// the manager's /system/configuration/devices.csv matcher knows how to read the report's identity
 /// (a PCI class triple vs a USB class triple are the same 24 bits but different
 /// namespaces) and which `bus` column a rule must name to bind it. `unknown` is
 /// the zero default, so an un-upgraded reporter fails to match rather than
@@ -96,7 +96,7 @@ pub const ChildAdded = extern struct {
     /// for an unregistered leaf (a USB port before the descriptor track).
     device_id: u64 = no_device,
     /// The vendor id (PCI vendor / USB idVendor), or 0 when the bus has no such
-    /// concept (ACPI). Carried so the manager's /etc/devices.csv matcher can bind
+    /// concept (ACPI). Carried so the manager's /system/configuration/devices.csv matcher can bind
     /// on vendor — a level the bus-native `identity` (a class triple) cannot express.
     vendor: u16 = 0,
     /// The device id (PCI device / USB idProduct), or 0. The most specific numeric