MinsOS v0.3.4

Updates install from Settings, and the battery page shows a measured figure.

- In-device updater: reads this device's own manifest, verifies against the
  MinsOS OTA certificate, stages and reboots. On the T970 the bundled
  crypto-less recovery installs it unattended.
- Battery health is recomputed from the fuel gauge at every boot; the cycle row
  is hidden rather than shown as a false zero.
- T870: the side-key fingerprint enrolment UI renders (display layer only).
- Third device: SM-T976B (gts7xl) ships alongside the T970 and T870.

Verified on hardware for gts7xlwifi (SM-T970). The other two rest on the build
gates and on tester reports.

USB-C DisplayPort is NOT fixed in this release - the redriver change had only
ever been in one of the three kernel build paths, and the shipped kernels have
CONFIG_REDRIVER unset. Both local paths carry it now; it lands with the next
kernel.