vendor: Libs/ from coa-ace3 + LibBabble-Zone / LibWindow; pin TOC version

Upstream Mapster relies on the CurseForge packager to fetch its libs
at release time; the raw repo has no Libs/ folder, so the freshly-
imported addon failed to load (LibStub missing).

- Vendored canonical Ace3 from coa-ace3 (11 libs Mapster's TOC loads:
  LibStub, CallbackHandler-1.0, AceAddon-3.0, AceEvent-3.0, AceHook-3.0,
  AceDB-3.0, AceDBOptions-3.0, AceLocale-3.0, AceGUI-3.0, AceConsole-3.0,
  AceConfig-3.0). This brings the CoA-compat FileDataID / BlizOptionsGroup
  parent-guard / Settings.* fallback / AceDB falsy-defaults patches.
- LibBabble-Zone-3.0 and LibWindow-1.1 vendored from the working PTR
  install (not part of Ace3).
- TOC: replaced @project-version@ CurseForge placeholder with the real
  release string 1.3.9-coa.2 so the in-game About panel reads correctly.

Mapster source itself was clean against the PORTING.md checklist
(no FDID calls, no retail-only globals, no Minimap mask trap, no CLEU
arg mismatch) — expected, since 1.3.9 was the WotLK-era release.

Mapster/Mapster.toc

@@ -6,7 +6,7 @@
 ## Author: Nevcairiel
 ## SavedVariables: MapsterDB
 ## X-Category: Map
-## Version: @project-version@
+## Version: 1.3.9-coa.2
 ## X-License: All rights reserved.
 
 ## OptionalDeps: Ace3, LibBabble-Zone-3.0, LibWindow-1.1