Module compile_view 

ViewDefinition JSON → PlanNode compiler.

Walks the SoF select tree producing a plan tree rooted in a PlanNode::Scan over resources. Per-clause logic:

• Plain select.column[] → column projections off the current focus.
• forEach/forEachOrNull → PlanNode::LateralUnnest over the parent.
• Nested select[] → contributes additional columns under the parent’s focus (or extends the row source if it has its own forEach).
• unionAll[] → PlanNode::Union with sibling column[] merged into each branch.
• Top-level where[].path → PlanNode::Filter applied to the root scan.

Stages 4–5 add chained-call collection threading, repeat:, and boundary functions.

Functions

build_plan

Build a plan tree for the given ViewDefinition JSON.