Advance SourceLocation past description so diagnostics point at the field, not the doc block

graphql-java’s FieldDefinition.getSourceLocation() (and the same call on type, input-field, and enum-value definitions) returns the start of the description block when one is present, not the line of the field name. Build-time validator logs and the R147 LSP diagnostic surface both inherit this: an error on a documented field highlights the opening """ of the doc block rather than the field, which is misleading in the console and visually wrong in the editor squiggle.

The fix lives in the BuildContext.locationOf(…​) family (graphitron-rewrite/graphitron/src/main/java/no/sikt/graphitron/rewrite/BuildContext.java:320-353) plus the inline def.getSourceLocation() call in validateConnectionType (graphitron-rewrite/graphitron/src/main/java/no/sikt/graphitron/rewrite/GraphitronSchemaValidator.java:224-225). A helper that walks past the description gives every validator error site the right location without touching the call sites.

Mechanically: when def.getDescription() != null, take description.getSourceLocation() as the start and advance past the description. Two delimiter forms to handle: single-line "…​" (advance by 1 line) and block string """…​""" (advance by 2 + newlineCountIn(description.getContent()) lines). Column resets to 1 on the new line. Test coverage: one unit test per delimiter form (single-line, single-line block, multi-line block) plus a "no description" pass-through case, asserting the returned SourceLocation line/column match what an editor would highlight.

Out of scope: comments (#) between the description and the field declaration. graphql-java’s parser doesn’t surface comment tokens on AST nodes, so any heuristic past the description is approximate. v1 of the fix assumes no comments in that gap; if it becomes a problem in practice, the precise fix is a tree-sitter pass over the source range, which is meaningful infrastructure for a one-line offset bug.

Non-goals: changing the SourceLocation shape itself, threading column-precise field-name offsets (still 1 because graphql-java doesn’t expose the name token’s column), or back-porting to legacy build-log paths outside the rewrite module.