* feat: implement slots instead of natural language
Replace the natural-language projection (`nl`) with engine-owned slot
completion: for a cursor position the engine classifies the slot being
edited (operand, operator, literal, member access, ...) and returns typed
options, literal facts and the expected type, for policies and graphs.
- zen-expression: new `slot` module (classification, literals, operators)
and a lenient lexer mode for incomplete input; `nl` removed
- Intellisense: typed diagnostic codes with arguments, richer inspect for
hover, dedicated parser error variants (messages unchanged)
- Engine: `Workspace::cursor_scope`, `slot`, `facts`; `rename_from` and
`references_from`; editor spans in UTF-16 units; renames reach imported
policies, `$nodes` reads, child graphs and output column heads; no `$root`
completion in policies
- Node bindings: `slot`, `facts`, `cursorScope`, `slotBatch` replace
`nl`, `nlTokenize`, `nlEncodeString`, `nlTokenizeBatch`
No change to expression evaluation: the VM, compiler, functions and the
default lexer path are untouched, and parser error messages keep their text.
* fix: harden slot classification, scopes and graph expectations
- restore master execution order; slot scopes hide writes of the edited
block and its dependents instead of relying on block ranking
- token-start editing gated by slot state; operator, list and operand
spans no longer splice into neighbouring tokens
- interval-aware bracket pairing for half-open and reversed intervals
- lenient lexer recovers from unknown characters (slots only)
- graph expected type follows switch and pass-through nodes and merges
compatible output schemas
- sibling inference caps distinct values and analyses lazily
- deterministic overload return type display
* fix: order policy blocks by entity reads through closures and relationships
- record reads for `#.field` in closures so entity fields read through
lists become dependencies
- link reads through derived lists (filter/map results) to the entity
fields they carry and order the list after those fields
- evaluate entity blocks on single relationships, and demand entity
paths for plain reads through relationships
- slot scopes keep the top-level variable when hiding written fields
stefan-gorules
