4.0.0-M4

• changed tsid output to lowercase (json + path-variables) - parsing stays case-insensitive
• tsid: invalid ids in json bodies / conversions now raise TsidDecodeException (404) instead of silent null - opt-out via tsid.invalid.allowed=true
• typescript-generator: @NotEmpty now marks fields required; also accepts spring @NonNull, jakarta @Nonnull + jspecify @NonNull - configurable via required-annotations property
• generator: wired custom-type-mappings property (was documented but inactive), exposed zod-infer-type-export + zod-infer type-suffix as properties
• Nulls: added notNull(Double), notNull(Collection), notEmpty(Collection/Map) + two-level get(source, a, b)