Replace libtotem with ClassicAPI's native totem tracker

ClassicAPI now ships GetTotemInfo/GetTotemTimeLeft/GetTotemDuration/
TargetTotem plus a native PLAYER_TOTEM_UPDATE event, backed by a
data-driven tracker (slot from the Spell.dbc summon effect, duration from
SpellDuration.dbc, and object-manager death detection). That's exactly
what libtotem hand-rolled -- and better -- so delete the library outright:
its spellid/icon tables, the CastSpellByName/CastSpell/UseAction hooks,
the SPELL_GO commit path, and the active-totem bookkeeping.

modules/totems.lua becomes a thin consumer of the native API:
- Driven by PLAYER_TOTEM_UPDATE; drop the shaman tick-poller that only
  existed because vanilla had no totem event.
- Fix the GetTotemInfo call sites: the native 1st return is tool presence,
  not "summoned", so key active state on name/start instead.
- Right-click a totem icon to TargetTotem it; tooltip shows remaining time
  via GetTotemTimeLeft.

modules/turtle-wow.lua: drop the Totemic Recall handler that poked
libtotem:Clean() -- the native tracker detects the totems despawning and
clears the slots itself. Also clean up the now-orphaned translation string
and a stale libtotem mention in libdebuff's comment.

libs/libdebuff.lua

@@ -16,7 +16,7 @@ setfenv(1, pfUI:GetEnvironment())
 -- non-player expirationTime). What remains in libdebuff is the cast-event
 -- bookkeeping consumed by GetBestAuraCast (libpredict HoT tracking) and the
 -- libdebuff_*_hooks broadcast surface (subscribers in actionbar / swingtimer
--- / libtotem react to SPELL_GO and SPELL_FAILED).
+-- react to SPELL_GO and SPELL_FAILED).
 
 -- return instantly when another libdebuff is already active
 if pfUI.api.libdebuff then return end