Remove all dead code: RaggedEnd machinery, redundant overrides

Massive cleanup removing code that is no longer reachable or duplicates
AbstractArray defaults:

Removed (dead code since lastindex returns plain Ints):
- RaggedEnd/RaggedRange structs and all Colon methods (caused 4 invalidations)
- _column_indices, _resolve_ragged_index, _resolve_ragged_indices
- _has_ragged_end, _resolve_ragged_end_args
- _ragged_getindex, _ragged_getindex_nm1dims, _ragged_getindex_full
- _checkbounds_ragged, _preserve_array_type, _padded_resolved_indices
- _is_ragged_dim, __parameterless_type

Removed (inherited from AbstractArray):
- size(::Adjoint{T, <:AbstractVectorOfArray}), getindex(::Adjoint{...})
- check_parent_index_match, SubArray constructor override
- CartesianIndex setindex! (handled by Int... method)
- broadcastable (AbstractArray is already broadcastable)
- mapreduce for N==1 case
- show(io, ::AbstractVectorOfArray) 2-arg (use AbstractArray display)

Added back:
- getindex/setindex! for CartesianIndex with more dims than ndims(A)
  (needed for heterogeneous inner arrays like [zeros(20), zeros(3,3,3)])

Invalidation trees: 8 → 4 (removed all Colon/RaggedEnd invalidations)
Net: -379 lines removed, +43 added

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ChrisRackauckas