libcamera: add the IMX896 sensor helper and properties (r3)

Teaches the software ISP's AGC the IMX896 gain law
(gain = 16384/(16384-code), inverted from the vendor driver and
round-tripped against all 3009 vendor gain-table entries, max error
0.049%) and adds the sensor properties (1.0um unit cell, test-pattern
map). Same shape as the OV13B10 pair; both verified to apply and
compile on v0.7.2 after 0001-0004.

The extracted-CCM tuning yaml is deliberately NOT packaged yet - the
color matrices come from the vendor Chromatix blob and the licensing
call is open (see the camera journal).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

aports/temp/libcamera/0006-libcamera-sensor-Add-IMX896-sensor-properties.patch

@@ -0,0 +1,41 @@
+From 262906b13ff727473679cf7895618e4745f3ba4c Mon Sep 17 00:00:00 2001
+From: Jorijn van der Graaf <jorijnvdgraaf@catcrafts.net>
+Date: Sun, 16 Aug 2026 20:49:31 +0200
+Subject: [PATCH] libcamera: sensor: Add IMX896 sensor properties
+
+Add the Sony IMX896 (Fairphone 6 main camera, 50 MP, 8192x6144) to
+the static properties database: 1.0 um unit cell and the test pattern
+modes exposed by the kernel driver (V4L2 menu indices map 1:1 to
+register 0x0600 values). Removes the "No static properties available
+for 'imx896'" warning.
+
+Assisted-by: Claude:claude-fable-5
+---
+ src/libcamera/sensor/camera_sensor_properties.cpp | 11 +++++++++++
+ 1 file changed, 11 insertions(+)
+
+diff --git a/src/libcamera/sensor/camera_sensor_properties.cpp b/src/libcamera/sensor/camera_sensor_properties.cpp
+index 2804315..63050c2 100644
+--- a/src/libcamera/sensor/camera_sensor_properties.cpp
++++ b/src/libcamera/sensor/camera_sensor_properties.cpp
+@@ -335,6 +335,17 @@ const CameraSensorProperties *CameraSensorProperties::get(const std::string &sen
+ 				.hblankDelay = 3
+ 			},
+ 		} },
++		{ "imx896", {
++			.unitCellSize = { 1000, 1000 },
++			.testPatternModes = {
++				{ controls::draft::TestPatternModeOff, 0 },
++				{ controls::draft::TestPatternModeSolidColor, 1 },
++				{ controls::draft::TestPatternModeColorBars, 2 },
++				{ controls::draft::TestPatternModeColorBarsFadeToGray, 3 },
++				{ controls::draft::TestPatternModePn9, 4 },
++			},
++			.sensorDelays = { },
++		} },
+ 		{ "ov2685", {
+ 			.unitCellSize = { 1750, 1750 },
+ 			.testPatternModes = {
+-- 
+2.55.0
+