fix: pcall GetSpecInfoByID, fix specs_per_class indexing, FDID->string

Three CoA 3.3.5 compatibility fixes for Details:

1. LibOpenRaid/LibOpenRaid.lua:1298 - C_ClassInfo.GetSpecInfoByID is now
   pcall-guarded. On CoA, specId can be non-numeric and the API errors
   out, taking the unit-info update with it. Matches the pcall pattern
   already shipped for GetSpecInfo(class, spec) in 7 sibling files.

2. Libs/DF/fw.lua:4257 - specs_per_class[index] was writing into the
   outer table by numeric index, clobbering keys and never populating
   the nested per-class table initialised on line 4253. Corrected to
   specs_per_class[class][index] so DF:GetClassSpecIDs(engClass) returns
   the right list.

3. Libs/DF/icongeneric.lua:211 - SetTexture(130759) passed a FileDataID
   to a 3.3.5 client that only resolves string paths, leaving icon
   borders blank. Replaced with the documented mapping
   [[Interface\COMMON\WhiteIconFrame]] (same path already used in
   frames/window_mythicplus/window_end_of_run.lua:358). Follows the
   FDID->string pattern shipped in coa-ace3 d422ad3.

Libs/DF/fw.lua

@@ -4254,7 +4254,7 @@ for _, class in ipairs(CLASS_SORT_ORDER) do
     for index, spec in ipairs(specs) do
         local ok, specInfo = pcall(C_ClassInfo.GetSpecInfo, class, spec)
         if ok and specInfo then
-		specs_per_class[index] = specInfo.ID
+		specs_per_class[class][index] = specInfo.ID
     end
         end
 end

Libs/DF/icongeneric.lua

@@ -208,7 +208,7 @@ detailsFramework.IconGenericMixin = {
             iconFrame.Border:ClearAllPoints()
             iconFrame.Border:SetPoint("topleft", iconFrame, "topleft", -1, 1)
             iconFrame.Border:SetPoint("bottomright", iconFrame, "bottomright", 1, -1)
-            iconFrame.Border:SetTexture(130759)
+            iconFrame.Border:SetTexture([[Interface\COMMON\WhiteIconFrame]])
             iconFrame.Border:SetTexCoord(0.296875, 0.5703125, 0, 0.515625)
             iconFrame.Border:SetDrawLayer("overlay", 7)
 

Libs/LibOpenRaid/LibOpenRaid.lua

@@ -1295,8 +1295,8 @@ end
             end
             role = "DAMAGER"
         else
-            local specInfo = C_ClassInfo.GetSpecInfoByID(specId or 0)
-            if specInfo then
+            local ok, specInfo = pcall(C_ClassInfo.GetSpecInfoByID, specId or 0)
+            if ok and specInfo then
                 specName = specInfo.Name
                 specDescription = specInfo.Description
                 specIcon = "Interface\\Icons\\"..specInfo.SpecFilename