v1.3.3 — static-analysis fixes

Kadena Ledger app v1.3.3 — static-analysis fixes, no functional change from v1.3.2

Static-analysis fixes, no functional change. Clang 21's analyser and clang-tidy reported three
findings in the 1.3.2 code; none is reachable by any input, and the device accepts, refuses and
shows exactly what 1.3.2 does.

Fixed

• The JSON reader refuses an empty buffer before scanning it, instead of testing the pointer only
  inside the NUL check. The caller already refuses an empty buffer first (parser_init_context),
  so no input reaches the new branch; the analyser could not see that and reported a null
  dereference in the trailing-bytes check.
• Two integer literals in the meta key check are written 1U instead of 1u.
• The version page reads 1.3.3.

Testing

• The full unit suite and the full Zemu matrix on all five models pass unchanged, except the
  snapshots of the version page, which now show 1.3.3.

Device hashes (deterministic)

Target	Application hash
nanos2 (Nano S+)	5de2186976638313a881faabe09bbf462df9ef8c5fae9451fa22b1a99d0efed4
nanox	49ff0568570a03e6fbb944cb689ada76d1248f6c585dc0b00a396b2a97d2ec6f
stax	53117d4b9e0fd38e3bfb0fd2cafbee56c7dac1b4611eb41ed42f94375379fadb
flex	599f7494a233b33a21a1bd4eeb66861c7adbde508d62aef057d3fa5aa95900ec
apex_p	c81f0c6b8d07248ce20860ab67edcbf8f1b3cf0a87f8263f1e7ae1812750ae4d