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/config/firmware-fallbacks.d/20-intel-dmc.toml

@@ -0,0 +1,9 @@
+# Intel GPU DMC display firmware fallback chains
+
+[[fallback]]
+pattern = "i915/adlp_dmc_ver2_16.bin"
+chain = ["i915/adlp_dmc_ver2_14.bin", "i915/adlp_dmc_ver2_12.bin"]
+
+[[fallback]]
+pattern = "i915/tgl_dmc_ver2_12.bin"
+chain = ["i915/tgl_dmc_ver2_10.bin", "i915/tgl_dmc_ver2_08.bin"]