fix(cbor): reject overflowing negative integers (#5039)

* fix(cbor): reject negative ints overflowing int64

CBOR encodes negative integers as "-1 - n" where n is uint64_t. When
n > INT64_MAX, casting to int64_t caused undefined behavior and silent
data corruption. Large negative values were incorrectly parsed as
positive integers (e.g., -9223372036854775809 became 9223372036854775807).

Add bounds check for to reject values that exceed int64_t
representable range, returning parse_error instead of silently
corrupting data.

Added regression test cases to verify.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

* chore: clarify tests

Add test for "n=0" case (result=-1) to cover the smallest magnitude
boundary. Update comments to explain CBOR 0x3B encoding and why
"result=0" is not possible. Clarify that n is an unsigned integer
in the formula "result = -1 - n" to help understanding the tests.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

* fix(cbor): extend overflow checks for other types

Extend negative integer overflow detection to all CBOR negative
integer cases (0x38, 0x39, 0x3A) for consistency with the existing
0x3B check.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

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Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>