chore: commit durable overlay state (configs, patches, recipe symlinks)

Pre-existing work from other sessions committed as durable state:
- local/config/drivers.d/ (8 driver configs)
- local/config/firmware-fallbacks.d/ (3 firmware configs)
- local/patches/base/, kernel/, relibc/ (new patch carriers)
- recipes/system/ symlinks (driver-params, acmd, ecmd, usbaudiod)

pkgar build artifacts and cache intentionally excluded.

local/patches/relibc/P3-spawn-cbindgen-fix.patch

@@ -0,0 +1,69 @@
+diff --git a/src/header/spawn/cbindgen.toml b/src/header/spawn/cbindgen.toml
+new file mode 100644
+index 0000000..a9f188f
+--- /dev/null
++++ b/src/header/spawn/cbindgen.toml
+@@ -0,0 +1,63 @@
++sys_includes = ["sys/types.h", "signal.h", "sched.h"]
++include_guard = "_SPAWN_H"
++after_includes = """
++typedef struct {
++    short __flags;
++    pid_t __pgrp;
++    sigset_t __sd;
++    sigset_t __ss;
++    struct sched_param __sp;
++    int __policy;
++    int __pad[16];
++} posix_spawnattr_t;
++
++typedef struct {
++    int __allocated;
++    int __used;
++    void *__actions;
++    int __pad[16];
++} posix_spawn_file_actions_t;
++"""
++trailer = """
++#define POSIX_SPAWN_RESETIDS    0x01
++#define POSIX_SPAWN_SETPGROUP   0x02
++#define POSIX_SPAWN_SETSIGDEF   0x04
++#define POSIX_SPAWN_SETSIGMASK  0x08
++#define POSIX_SPAWN_SETSCHEDPARAM 0x10
++#define POSIX_SPAWN_SETSCHEDULER  0x20
++
++int posix_spawn(pid_t *__restrict, const char *__restrict,
++                const posix_spawn_file_actions_t *,
++                const posix_spawnattr_t *__restrict,
++                char *const __restrict[], char *const __restrict[]);
++int posix_spawnp(pid_t *__restrict, const char *__restrict,
++                 const posix_spawn_file_actions_t *,
++                 const posix_spawnattr_t *__restrict,
++                 char *const __restrict[], char *const __restrict[]);
++int posix_spawnattr_init(posix_spawnattr_t *);
++int posix_spawnattr_destroy(posix_spawnattr_t *);
++int posix_spawnattr_setflags(posix_spawnattr_t *, short);
++int posix_spawnattr_getflags(const posix_spawnattr_t *__restrict, short *__restrict);
++int posix_spawnattr_setpgroup(posix_spawnattr_t *, pid_t);
++int posix_spawnattr_getpgroup(const posix_spawnattr_t *__restrict, pid_t *__restrict);
++int posix_spawnattr_setsigdefault(posix_spawnattr_t *__restrict, const sigset_t *__restrict);
++int posix_spawnattr_getsigdefault(posix_spawnattr_t *__restrict, sigset_t *__restrict);
++int posix_spawnattr_setsigmask(posix_spawnattr_t *__restrict, const sigset_t *__restrict);
++int posix_spawnattr_getsigmask(posix_spawnattr_t *__restrict, sigset_t *__restrict);
++int posix_spawn_file_actions_init(posix_spawn_file_actions_t *);
++int posix_spawn_file_actions_destroy(posix_spawn_file_actions_t *);
++int posix_spawn_file_actions_adddup2(posix_spawn_file_actions_t *, int, int);
++int posix_spawn_file_actions_addclose(posix_spawn_file_actions_t *, int);
++int posix_spawn_file_actions_addopen(posix_spawn_file_actions_t *__restrict,
++                                      int, const char *__restrict, int, mode_t);
++"""
++language = "C"
++style = "Type"
++no_includes = true
++cpp_compat = true
++
++[enum]
++prefix_with_name = true
++
++[export]
++include = []