Add SymbolInformation for local symbols per SCIP spec (#167)

Add SymbolInformation for local symbols per SCIP spec

According to the SCIP specification, Document.symbols should contain all
symbols defined within the document, including local symbols (local variables,
parameters, etc.). Local symbols use the format 'local <id>' and must be
included in Document.symbols for proper SCIP compliance.

This change adds SymbolInformation entries for all local symbols to each
document, fixing scip lint errors about missing symbol definitions for
local 0, local 1, etc.

Author: jupblb

AGENTS.md

@@ -0,0 +1,39 @@
+# scip-go Development Guide
+
+## Commands
+
+- **Build**: `go build ./cmd/scip-go`
+- **Test all**: `go test ./...`
+- **Test single package**: `go test ./internal/index`
+- **Update snapshots**: `go test ./internal/index -update-snapshots`
+- **Install**: `go install ./cmd/scip-go`
+- **Version check**: `go version` (uses Go 1.24.3)
+
+## Testing
+
+- **Snapshot testing**: Primary testing method using
+  `internal/testdata/snapshots` directory with `internal/index/scip_test.go` as
+  the test runner
+- **Test data**: Located in `internal/testdata/` with test cases as
+  subdirectories
+- **Update snapshots**: Run with `-update-snapshots` flag to regenerate expected
+  outputs
+- **Filter tests**: Use `-filter <name>` to run specific test cases
+
+## Architecture
+
+SCIP (Source Code Intelligence Protocol) indexer for Go. Main entry point is
+`cmd/scip-go/main.go`. Key packages: `internal/index` (core indexing),
+`internal/loader` (package loading), `internal/visitors` (AST traversal),
+`internal/document` (SCIP document generation).
+
+## Code Style
+
+- Package naming: lowercase, single word preferred (e.g., `index`, `loader`,
+  `symbols`)
+- Imports: grouped by std library, third-party, then internal packages with
+  blank lines
+- Test files: use `package_test` convention for black-box testing
+- Embed files: use `//go:embed` for version.txt and similar resources
+- Error handling: return explicit errors, no panics in library code
+- Logging: use `charmbracelet/log` for structured logging

internal/visitors/visitor_file.go

@@ -18,8 +18,10 @@ import (
 	"golang.org/x/tools/go/packages"
 )
 
-const symbolDefinition = int32(scip.SymbolRole_Definition)
-const symbolReference = int32(scip.SymbolRole_ReadAccess)
+const (
+	symbolDefinition = int32(scip.SymbolRole_Definition)
+	symbolReference  = int32(scip.SymbolRole_ReadAccess)
+)
 
 func NewFileVisitor(
 	doc *document.Document,
@@ -336,6 +338,12 @@ func (v *fileVisitor) ToScipDocument() *scip.Document {
 	}
 
 	documentSymbols := v.pkgSymbols.SymbolsForFile(documentFile)
+	for _, localSymbol := range v.locals {
+		documentSymbols = append(documentSymbols, &scip.SymbolInformation{
+			Symbol: localSymbol,
+		})
+	}
+
 	return &scip.Document{
 		Language:     "go",
 		RelativePath: v.doc.RelativePath,