Fix/object error code

[Unclebaffa]

closes #216

I have resolved this task by pulling the full list of host object error codes from Stellar Soroban (the ScHostObjErrorCode enum) and integrating them into both the taxonomy database and the CLI decoding mappings.

1. Object Error Taxonomy Code Listing
   The full set of host object errors is defined by the following variants and numeric codes:

Code 0 (UnknownError): General/unclassified host object failure.
Code 1 (UnknownReference): Handle references a non-existent or out-of-scope object.
Code 2 (UnexpectedType): Type mismatch (e.g. Map handle passed where Vector was expected).
Code 3 (ObjectCountExceedsU32Max): Max limit of host objects exceeded (u32::MAX).
Code 4 (ObjectNotExist): Requested object was missing or garbage collected.
Code 5 (VecIndexOutOfBound): Accessing an index greater than or equal to a vector/byte array length.
Code 6 (ContractHashWrongLength): Passing a hash or address of incorrect length (must be 32 bytes).

2. Changes Implemented
   Taxonomy Database (

object.toml
):

Fixed code 0 to map to UnknownError (it was previously acting as a placeholder for IndexBounds).
Added complete entries for all 7 codes (0 through 6) with detailed descriptions, likelihood-rated common causes, and difficulty-rated suggested fixes.
Rust Mappings (

object.rs
):

Created the new mapping file with OBJECT_ERROR_DETAILS array and lookup function.
Added unit tests asserting correct lookup behavior for known and unknown object error codes.
Module Registration (

mod.rs
):

Registered the object mapping module alongside other error code mapping categories.
Decoder Support (

host_error.rs
):

Updated the object error match arm inside HostError::summary() to use the new crate::decode::mappings::object::lookup look-up mechanism.
Updated the unit test assertions to reflect the correct summaries for code 0 (UnknownError) and code 5 (VecIndexOutOfBound).