Modernize power-API usage onto ClassicAPI

- Replace all UnitMana/UnitManaMax calls with UnitPower/UnitPowerMax. The
  no-arg form returns the unit's primary power from the same field vanilla's
  UnitMana read, so these are behavior-preserving. Drops two dead
  UnitMana/UnitManaMax local caches in nameplates.lua.
- Replace magic power-type numbers (0/1/2/3) with Enum.PowerType.Mana/Rage/
  Focus/Energy in the GetUnitStats branches, the power-bar color block, the
  druid mana bar, GetStatusValue's powerdyn, and energytick's mode checks.

modules/energytick.lua

@@ -32,10 +32,10 @@ pfUI:RegisterModule("energytick", function()
   energytick:RegisterEvent("CHAT_MSG_SPELL_PERIODIC_SELF_BUFFS")
 
   energytick:SetScript("OnEvent", function()
-    if UnitPowerType("player") == 0 and C.unitframes.player.manatick == "1" then
+    if UnitPowerType("player") == Enum.PowerType.Mana and C.unitframes.player.manatick == "1" then
       this.mode = "MANA"
       this:Show()
-    elseif UnitPowerType("player") == 3 and C.unitframes.player.energy == "1" then
+    elseif UnitPowerType("player") == Enum.PowerType.Energy and C.unitframes.player.energy == "1" then
       this.mode = "ENERGY"
       this:Show()
     else
@@ -51,11 +51,11 @@ pfUI:RegisterModule("energytick", function()
     end
 
     if event == "PLAYER_ENTERING_WORLD" then
-      this.lastMana = UnitMana("player")
+      this.lastMana = UnitPower("player")
     end
 
     if (event == "UNIT_MANA" or event == "UNIT_ENERGY") and arg1 == "player" then
-      this.currentMana = UnitMana("player")
+      this.currentMana = UnitPower("player")
       local diff = 0
       if this.lastMana then
         diff = this.currentMana - this.lastMana
@@ -64,7 +64,7 @@ pfUI:RegisterModule("energytick", function()
       if this.mode == "MANA" and diff < 0 then
         this.target = 5
       elseif this.mode == "MANA" and diff > 0 then
-        if UnitMana("player") >= UnitManaMax("player") then
+        if UnitPower("player") >= UnitPowerMax("player") then
           this.start = nil
           this.spark:SetAlpha(0)
           this:Hide()
@@ -105,7 +105,7 @@ pfUI:RegisterModule("energytick", function()
 
     if this.current > this.max then
       -- Don't restart tick timer if mana is full
-      if this.mode == "MANA" and UnitMana("player") >= UnitManaMax("player") then
+      if this.mode == "MANA" and UnitPower("player") >= UnitPowerMax("player") then
         this.start = nil
         this.spark:SetAlpha(0)
         return

modules/nameplates.lua

@@ -15,8 +15,6 @@ pfUI:RegisterModule("nameplates", function ()
   local UnitCanAssist = UnitCanAssist
   local UnitHealth = UnitHealth
   local UnitHealthMax = UnitHealthMax
-  local UnitMana = UnitMana
-  local UnitManaMax = UnitManaMax
   local pairs = pairs
   local tonumber = tonumber
   local strlower = strlower