rust-bitcoin

This commit is a routine library cleanup: it adds two missing public re-exports (`parse` and `result::{self, NumOpResult}`) from the `units` crate into the `primitives` crate so that all `units` items are consistently available through `primitives`. There is no security-relevant change.

This commit is a routine cleanup of how Bitcoin amount-related error types are exposed to users of the Rust Bitcoin library. It moves error types into a dedicated `amount::error` submodule and adjusts re-exports so the public API is better organized. There is no indication this fixes a security vulnerability or changes how amounts are validated.

This commit makes a small internal Rust module named `fee` private instead of public. The module contained no usable types or functions—only a macro call generating internal math operations. This is a routine API cleanup that removes an accidentally exposed, empty-looking module from the public interface. There is no security bug being fixed here.

This commit is a routine code organization fix. It adjusts which type names are publicly re-exported (made visible) from the 'block' modules of the library so that the naming convention is consistent across crates. No security issue is present.

This commit is a routine library reorganization: it moves some error/result helper types into a newly public `result` submodule and removes their old re-exports from the crate root. There is no change to how calculations are performed, no bug fix, and no security-sensitive behavior is introduced.

This commit is a simple renaming of two fields in the Transaction struct from singular 'input'/'output' to plural 'inputs'/'outputs'. It is a stylistic/API-breaking change, not a security fix or vulnerability. The diff updates all internal usages, examples, tests, and fuzz targets consistently. There is one stray file 'bitcoin/src/ex' containing the letter 't' that appears to be an accidental addition, but it is harmless.