feat(cli): add du command for disk usage reporting

docs/usage/commands/du.md

@@ -0,0 +1,90 @@
+# du
+
+`du` (disk usage) reports the disk space used by files and directories.
+
+## Usage
+
+```sh
+du [OPTIONS]... [FILE]...
+```
+
+## Description
+
+By default, `du` prints human-readable sizes for each file and directory it encounters, starting from the current directory (`.`) if no path is given.
+
+## Options
+
+| Option | Description |
+| :--- | :--- |
+| `-s, --summarize` | Show only a total for each argument, suppressing per-entry output. |
+| `-a, --all` | Write counts for all files, not just directories. |
+| `-d, --max-depth=N` | Stop at depth N; show only entries at or above depth N. |
+| `-c, --total` | Print a grand total after all arguments have been processed. |
+| `-b, --bytes` | Print sizes in exact bytes instead of human-readable units. |
+| `-h, --human-readable` | Accepted for compatibility; human-readable is the default. |
+| `--help` | Display usage information and exit. |
+
+## Output Format
+
+Each line shows a size followed by the path:
+
+```
+SIZE    PATH
+```
+
+Sizes are formatted as `B`, `KB`, `MB`, or `GB` by default, with one decimal place when appropriate (e.g., `1.5 GB`). The `-b` option overrides this to show exact byte counts.
+
+## Examples
+
+Show disk usage for the current directory:
+
+```sh
+du
+```
+
+Show disk usage for a specific path:
+
+```sh
+du /bin
+```
+
+Show only totals per argument (`-s`):
+
+```sh
+du -s /bin /home
+```
+
+Show all files and directories recursively (`-a`):
+
+```sh
+du -a /bin
+```
+
+Limit output to depth 1 (`-d`):
+
+```sh
+du -d 1 /
+```
+
+Print a grand total after processing (`-c`):
+
+```sh
+du -c /bin /home
+```
+
+Show exact byte counts (`-b`):
+
+```sh
+du -b /bin
+```
+
+## How It Works
+
+`du` uses `sys_get_file_info()` to read file sizes and `sys_list()` to enumerate directory contents recursively. The command skips the synthetic `.` and `..` entries and continues processing remaining paths if one path is inaccessible, printing an error for the failed path.
+
+The size reported is the **apparent file size** (the logical size stored in the directory entry), not the allocated disk blocks. This is consistent with how BoredOS reports file sizes through the filesystem API.
+
+## Exit Status
+
+- `0`: Success
+- `1`: One or more paths could not be accessed or listed

docs/usage/terminal.md

@@ -54,6 +54,7 @@ Below are some of the most used commands available in `/bin`:
 | `mkdir` | Create a new directory. |
 | `man` | View the manual for a specific command (e.g., `man ls`). |
 | `lsblk` | List block devices and partitions with size, type, filesystem, label, and flags. |
+| `du` | Report disk usage for files and directories, recursively. |
 | `sysfetch` | Display system and hardware information. |