fix: restore table.getn/setn for Ace2 stack so VanillaGuide loads on 3.3.5 Lua 5.1

WoW 3.3.5 Lua 5.1 runtime has table.setn as an error stub ("'setn' is obsolete")
and table.getn missing/erroring. The embedded Ace2 libs (AceLibrary, AceOO, AceEvent,
AceConsole, AceDebug, AceDB, Tablet-2.0) all assign table_setn = table.setn at module
scope when GetBuildInfo() does not start with "2." — causing AceOO-2.0 to crash at
line 546 before any library can register, then cascading to AceConsole/FuBarPlugin.

Add Lua50Compat.lua as the first TOC entry to unconditionally overwrite table.setn
(no-op) and table.getn (returns #t) before any lib loads. Also shims
table.foreach/foreachi in case future libs need them. Verified with LuaJIT 5.1:
AceLibrary + AceOO load cleanly; all other libs stop only at WoW-API boundaries
(not at obsolete-call errors).

VanillaGuide/Lua50Compat.lua

@@ -0,0 +1,42 @@
+-- Lua50Compat.lua
+-- Loaded FIRST (see VanillaGuide.toc) to restore Lua 5.0 table functions that
+-- the WoW 3.3.5 / Project Ascension Lua 5.1 runtime has made obsolete.
+--
+-- table.setn existed in 5.0 to manually hint the array length; in 5.1 the
+-- length operator (#) is authoritative and table.setn is a stub that raises
+-- "attempt to call a nil value" or "'setn' is obsolete".  Overwrite it with a
+-- no-op unconditionally so Ace2 libs (AceOO, AceEvent, AceConsole, AceDebug,
+-- AceLibrary, AceDB, Tablet-2.0) can assign the local alias at module load
+-- time without erroring.
+--
+-- table.getn existed in 5.0 as the canonical length function; in 5.1 it was
+-- removed (or kept as an error stub on some runtimes).  Replace it with the
+-- equivalent # operator.
+--
+-- table.foreach / table.foreachi were removed in 5.1 as well; guard them in
+-- case any lib uses them (none currently do, but safe to shim anyway).
+
+-- Unconditional overwrite -- even if these slots exist they may raise.
+table.setn = function() end
+
+table.getn = function(t)
+    return #t
+end
+
+if not table.foreach then
+    table.foreach = function(t, f)
+        for k, v in pairs(t) do
+            local ret = f(k, v)
+            if ret then return ret end
+        end
+    end
+end
+
+if not table.foreachi then
+    table.foreachi = function(t, f)
+        for i = 1, #t do
+            local ret = f(i, t[i])
+            if ret then return ret end
+        end
+    end
+end