fix(ir): avoid recursive isl range traversal

[zhen8838]

Why

• Fixes parser: tile() bound cta.x * (M // BX) recurses until RecursionError (dim_to_isl_expr <-> dim_range) #182.
• Rendering an integer Binary(MUL) could call the separate range visitor, which rendered the same node again and recursed indefinitely.

What

• Use one bottom-up dimension visitor for isl rendering and parameter-bound collection.
• Derive finite ranges from the rendered isl expression and retain interval arithmetic only for opaque non-affine multiplication.
• Prove parameter-independent constant subexpressions with isl and emit their integer value before multiplication, preserving mesh-coordinate dependence.
• Exercise the reported inline floor-division form in the existing persistent GEMM fixture.

Contract

• Public signatures and half-open range semantics are unchanged.
• Symbolic divisors remain unsupported, and non-affine products remain opaque parameters with conservative bounds.

Risk

• None.