Add configurable topdata wiki visibility policy (#4)

## Summary
- add YAML-backed generated wiki visibility policies for topdata datasets
- centralize page and reference eligibility through a visibility index
- cover eligibility helpers, metadata precedence, derived feat sets, and link suppression with toolkit tests

## Verification
- go test ./...
- module ./validate-topdata.sh with the feature toolkit binary
- module ./build-wiki.sh --force with the feature toolkit binary

Companion module branch: codex-wiki-visibility.

Reviewed-on: https://gitea.westgate.pw/ShadowsOverWestgate/sow-tools/pulls/4
Co-authored-by: vickydotbat <vickydotbat@tutamail.com>
Co-committed-by: vickydotbat <vickydotbat@tutamail.com>

internal/topdata/wiki_tables.go

@@ -607,11 +607,12 @@ func tokenizeWikiExpr(expr string) []wikiExprToken {
 }
 
 type wikiExprParser struct {
-	tokens    []wikiExprToken
-	pos       int
-	row       map[string]any
-	ctx       *wikiContext
-	renderCtx wikiTableRenderContext
+	tokens             []wikiExprToken
+	pos                int
+	row                map[string]any
+	ctx                *wikiContext
+	renderCtx          wikiTableRenderContext
+	allowMissingFields bool
 }
 
 func (p *wikiExprParser) peek() wikiExprToken {
@@ -771,12 +772,21 @@ func (p *wikiExprParser) resolveField(name string) (any, error) {
 	if name == "HasSpellProgression" {
 		return hasSpellProgression(p.renderCtx.Page.Row), nil
 	}
+	switch name {
+	case "true":
+		return true, nil
+	case "false":
+		return false, nil
+	}
 	if value, ok := lookupField(p.row, name); ok {
 		return value, nil
 	}
 	if value, ok := lookupField(p.renderCtx.Page.Row, name); ok {
 		return value, nil
 	}
+	if p.allowMissingFields {
+		return nil, nil
+	}
 	return nil, fmt.Errorf("missing field %q", name)
 }
 
@@ -800,6 +810,9 @@ func (p *wikiExprParser) callHelper(name string, args []any) (any, error) {
 	case "link":
 		if len(args) == 1 {
 			key := stringifyWikiTableValue(args[0])
+			if p.ctx != nil && !p.ctx.canReferenceWikiKey(key) {
+				return "", nil
+			}
 			if pageID := wikiPageIDForKey(key); pageID != "" {
 				key = pageID
 			}
@@ -811,6 +824,9 @@ func (p *wikiExprParser) callHelper(name string, args []any) (any, error) {
 			if key == "" {
 				return label, nil
 			}
+			if p.ctx != nil && !p.ctx.canReferenceWikiKey(key) {
+				return "", nil
+			}
 			if pageID := wikiPageIDForKey(key); pageID != "" {
 				key = pageID
 			}
@@ -870,11 +886,46 @@ func (p *wikiExprParser) callHelper(name string, args []any) (any, error) {
 			return args[1], nil
 		}
 		return args[0], nil
+	case "present":
+		if len(args) != 1 {
+			return nil, fmt.Errorf("present expects 1 argument")
+		}
+		return presentWikiValue(args[0]), nil
+	case "all_present":
+		if len(args) == 0 {
+			return nil, fmt.Errorf("all_present expects at least 1 argument")
+		}
+		for _, value := range args {
+			if !presentWikiValue(value) {
+				return false, nil
+			}
+		}
+		return true, nil
+	case "any_present":
+		if len(args) == 0 {
+			return nil, fmt.Errorf("any_present expects at least 1 argument")
+		}
+		for _, value := range args {
+			if presentWikiValue(value) {
+				return true, nil
+			}
+		}
+		return false, nil
 	default:
 		return nil, fmt.Errorf("unknown helper %q", name)
 	}
 }
 
+func presentWikiValue(value any) bool {
+	if isNullLike(value) {
+		return false
+	}
+	if text, ok := value.(string); ok {
+		return strings.TrimSpace(text) != ""
+	}
+	return value != nil
+}
+
 func ordinalWikiTableValue(value int) string {
 	suffix := "th"
 	if value%100 < 11 || value%100 > 13 {