[CubeCL][P1.3] Implement views, slicing, indexing, gather, reshape, and transpose

Objective

Implement the existing view/index/transform surface on CubeCL while preserving shape, stride, bounds, aliasing and materialization semantics.

Acceptance criteria

• Operation inventory covers every applicable OpenCL/public view and indexing operation.
• Contiguous and non-contiguous inputs, negative/empty ranges where supported, repeated gather indices, bounds failures, reshape compatibility and transpose permutations are tested.
• Aliasing/materialization behavior is documented and matches the public API.
• Composed view chains produce the same results and typed failures as host execution.
• Transfers/materializations are observable so later fusion planning can identify boundaries.
• No OpenCL code is removed.

Parent: #35

Tembo execution contract

automation:
  eligible: true
  executor_profile: tembo
  readiness: blocked
  primary_repository: TinyChain-Inc/ha-ndarray
  base_branch: main
  writable_scope:
    - src/cubecl/view/**
    - src/cubecl/index/**
    - src/cubecl/transform/**
    - src/array.rs
    - src/ops.rs
    - tests/conformance/**
  prerequisites:
    - "#50 designated accelerator validation lane"
    - "#41"
  concurrency_group: cubecl-views-indexing
  required_commands:
    - "cargo fmt --all -- --check"
    - "cargo test --no-default-features --features cubecl"
    - "cargo test --all-features"
  evidence:
    cpu_conformance: required
    accelerator_conformance: required-on-designated-runner
    actual_browser: not-required
    benchmark_report: not-required
    exact_hardware_and_driver_identity: required
  external_actions: none
  draft_pr_only: true
  completion_authority: human
  budget:
    size: large
    max_revisions: 3
    max_wall_minutes: 180

Start by checking prerequisites #50 and #41, then inventory the existing implementations under src/cubecl/view/, src/cubecl/index/, src/cubecl/transform/, src/array.rs, and src/ops.rs. Add or extend tests under tests/conformance/ and run the required cargo fmt and cargo test commands. Done means all applicable operations, composed semantics, failures, aliasing, materialization, and CPU/accelerator conformance evidence meet the acceptance criteria.