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/project/effective.go

@@ -40,6 +40,7 @@ const (
 	DefaultTopDataWikiLinkStrategy         = "preserve_westgate_wiki_links"
 	DefaultTopDataWikiNamespacesFile       = "namespaces.yaml"
 	DefaultTopDataWikiTablesFile           = "tables.yaml"
+	DefaultTopDataWikiVisibilityFile       = "visibility.yaml"
 	DefaultTopDataWikiTemplatesDir         = "templates"
 	DefaultTopDataWikiManualSectionsDir    = "manual-sections"
 	DefaultTopDataWikiStaleDefault         = "report"
@@ -247,6 +248,7 @@ func (p *Project) EffectiveConfig() EffectiveConfig {
 			LinkStrategy:         defaultString(p.Config.TopData.Wiki.LinkStrategy, DefaultTopDataWikiLinkStrategy),
 			NamespacesFile:       defaultString(p.Config.TopData.Wiki.NamespacesFile, DefaultTopDataWikiNamespacesFile),
 			TablesFile:           defaultString(p.Config.TopData.Wiki.TablesFile, DefaultTopDataWikiTablesFile),
+			VisibilityFile:       defaultString(p.Config.TopData.Wiki.VisibilityFile, DefaultTopDataWikiVisibilityFile),
 			TemplatesDir:         defaultString(p.Config.TopData.Wiki.TemplatesDir, DefaultTopDataWikiTemplatesDir),
 			ManualSectionsDir:    defaultString(p.Config.TopData.Wiki.ManualSectionsDir, DefaultTopDataWikiManualSectionsDir),
 			TitlePrefixMinLength: defaultInt(p.Config.TopData.Wiki.TitlePrefixMinLength, DefaultTopDataWikiTitlePrefixMinLength),
@@ -484,6 +486,7 @@ func markMissingDefaults(provenance ConfigProvenance) {
 		"topdata.wiki.link_strategy":                     DefaultTopDataWikiLinkStrategy,
 		"topdata.wiki.namespaces_file":                   DefaultTopDataWikiNamespacesFile,
 		"topdata.wiki.tables_file":                       DefaultTopDataWikiTablesFile,
+		"topdata.wiki.visibility_file":                   DefaultTopDataWikiVisibilityFile,
 		"topdata.wiki.templates_dir":                     DefaultTopDataWikiTemplatesDir,
 		"topdata.wiki.manual_sections_dir":               DefaultTopDataWikiManualSectionsDir,
 		"topdata.wiki.title_prefix_min_length":           "3",