Bring Symbols enum and module-base docs back in line with reality

Three small consistency fixes surfaced by a code-review pass:

- Symbols::Birth comment said "asterisk" but the value is BLACK STAR
  (★, U+2605). Update the comment so a future reader doesn't switch
  to a literal "*" and silently change the rendered glyph.
- MARRIAGE_DATE_UNKNOWN was a `public const string` on a backed enum
  while every other entry is a real case, forcing consumers to drop
  ->value at the one call site. Promote it to `case MarriageDateUnknown`
  so cases() / from() / value access stay uniform; updated the single
  upstream consumer (DateProcessor) to use ->value.
- README.md and AGENTS.md still advertised Model/Node + Model/NodeData
  even though those classes only live inside the chart-module repos
  and were never part of module-base. Replace with the actual public
  surface (Symbols enum + NameAbbreviation strategy enum). Sister
  AGENTS.md files in the three chart modules were sed-fixed for the
  matching MarriageDateUnknown rename in their respective repos.

Author: magicsunday

AGENTS.md

@@ -1,5 +1,5 @@
 ## Overview
-This repository hosts `magicsunday/webtrees-module-base` — a shared PHP library consumed by `webtrees-fan-chart`, `webtrees-pedigree-chart`, and `webtrees-descendants-chart`. It contains the common processors (Date, Name, Image, Place), models (Node, Symbols), and module helpers (VersionInformation) those modules use to render genealogy charts. No JavaScript, no asset pipeline — pure PHP.
+This repository hosts `magicsunday/webtrees-module-base` — a shared PHP library consumed by `webtrees-fan-chart`, `webtrees-pedigree-chart`, and `webtrees-descendants-chart`. It contains the common processors (Date, Name, Image, Place), models (Symbols, NameAbbreviation), and module helpers (VersionInformation) those modules use to render genealogy charts. No JavaScript, no asset pipeline — pure PHP.
 
 ## Setup/env
 - PHP 8.3 - 8.5 with extension `dom` is required; composer installs dependencies into `.build/vendor` and binaries into `.build/bin`.
@@ -39,8 +39,8 @@ tests/
 - **`PlaceProcessor`** — place name shortening (configurable parts) for chart labels.
 
 ### Models
-- **`Model/Symbols`** — backed enum for genealogical symbols (Birth ★, Death †, etc.) plus the `MARRIAGE_DATE_UNKNOWN` sentinel.
-- **`Model/Node`, `Model/NodeData`** — used by chart modules for tree-node serialization to D3 (each module wraps these in its own DataFacade).
+- **`Model/Symbols`** — backed enum for genealogical symbols (Birth ★, Death †, en-dash separator, MarriageDateUnknown sentinel).
+- **`Model/NameAbbreviation`** — backed enum + `resolve()` helper for the chart-label name-abbreviation strategy (auto / given / surname). Each chart module wires its own NodeData class; this base library only ships the strategy enum.
 
 ### Modules
 - **`Module/VersionInformation`** — checks GitHub releases for newer module versions, with file cache. Used by all three chart modules' admin pages.

README.md

@@ -51,8 +51,8 @@ class Module extends AbstractModule implements ModuleCustomInterface, ModuleAsse
 - **`PlaceProcessor`** — place name shortening (configurable parts) for chart labels
 
 ### `src/Model/`
-- **`Symbols`** — backed enum for genealogical symbols (Birth ★, Death †, MARRIAGE_DATE_UNKNOWN sentinel, …)
-- **`Node`, `NodeData`** — tree-node value objects with D3-friendly JSON serialisation, used by chart modules' `DataFacade`
+- **`Symbols`** — backed enum for genealogical symbols (Birth ★, Death †, en-dash separator, MarriageDateUnknown sentinel)
+- **`NameAbbreviation`** — backed enum + `resolve()` helper for the name-abbreviation strategy used in chart labels (auto / given-first / surname-first)
 
 ### `src/Module/`
 - **`VersionInformation`** — checks GitHub releases for newer module versions, with file cache (used by the chart modules' admin pages)

src/Model/Symbols.php

@@ -21,7 +21,7 @@
 enum Symbols: string
 {
     /**
-     * Birth symbol (asterisk).
+     * Birth symbol (black star).
      */
     case Birth = "\u{2605}";
 
@@ -40,5 +40,5 @@ enum Symbols: string
      * Consumers that render the marriage symbol can check for this sentinel
      * to display the symbol without an accompanying date string.
      */
-    public const string MARRIAGE_DATE_UNKNOWN = '?';
+    case MarriageDateUnknown = '?';
 }

src/Processor/DateProcessor.php

@@ -284,7 +284,7 @@ public function getFormattedMarriageDate(): string
 
     /**
      * Returns the marriage date of the parents formatted with the generation-aware
-     * compact format. Returns Symbols::MARRIAGE_DATE_UNKNOWN ("?") when a MARR fact
+     * compact format. Returns Symbols::MarriageDateUnknown ("?") when a MARR fact
      * exists but carries no date, so consumers can distinguish "married, date unknown"
      * from "no marriage fact at all". Empty string when no parent family exists.
      *
@@ -300,7 +300,7 @@ public function getFormattedMarriageDateOfParents(): string
         }
 
         if (($family !== null) && $family->facts(['MARR'])->isNotEmpty()) {
-            return Symbols::MARRIAGE_DATE_UNKNOWN;
+            return Symbols::MarriageDateUnknown->value;
         }
 
         return '';