fix: blank lines inside mappings orphan all following entries

[isutare412]

Symptom

In any OpenAPI spec with blank lines between schema entries (very common in hand-written specs), textDocument/definition and textDocument/references on $ref values silently return nothing for everything below the first blank line inside components. Blank lines between top-level sections are harmless (the next section is at indent 0 anyway), which is why the bundled testdata/petstore.yaml never caught it.

Minimal reproduction — without the fix, a definition request on a $ref to #/components/schemas/Bar returns null because Document.Locate cannot resolve it:

openapi: 3.0.0
components:
  schemas:
    Foo:
      type: object

    Bar:
      type: object

Cause

In Parse (internal/analysis/yaml/yaml.go), a blank line parses with indent 0 (len("") == 0). The parent-stack pop loop then treats it as an indent-0 mapping key: it pops the entire stack and registers the blank line as a new root under the empty key. Every line after the blank line is re-parented under that phantom root, so Locate can no longer resolve it.

Fix

Skip whitespace-only lines in the structure pass. They are still appended to document.Lines first, because Lines is indexed by LSP line number in internal/analysis/handler.go (document.Lines[params.Position.Line]).

Verification

• New test TestRefs_BlankLineBetweenSchemas fails before the fix (could not locate #/components/schemas/Bar) and passes after.
• go test ./... passes across the whole repo.
• Validated against real hand-written OpenAPI specs via a raw LSP stdio client: $ref resolution went from 0/103, 0/95, 0/103 to 103/103, 95/95, 103/103. A machine-generated spec without blank lines was 58/58 both before and after (no regression).

[isutare412]

@armsnyder Could you please check this?