Add learned combo duration system - saves actual durations per CP

Major enhancement: System now learns actual combo finisher durations and
saves them per combo point level (1-5 CP).

**New SavedVariable:**
- CleveRoids_ComboDurations[spellID][comboPoints] = duration
- Persists between sessions
- Uses learned durations before calculated formulas

**ComboPointTracker.lua:**
- Added GetLearnedComboDuration(spellID, cp) - fetch learned duration
- Updated CalculateComboScaledDurationByID to check learned first
- Falls back to formula if not learned yet

**Utility.lua (libdebuff):**
- UNIT_CASTEVENT handler stores combo points in learnCastTimers
- RAW_COMBATLOG fade handler learns combo durations when spells expire
- Stores learned duration keyed by [spellID][comboPoints]
- Debug message shows "Learned combo spell X at Y CP = Zs"

**Core.lua:**
- New command: /cleveroid combolearn - Show all learned combo durations
- Lists each spell with all learned CP levels (1-5)
- Shows which durations have been learned vs not yet

**Benefits:**
- Debuff conditionals like [debuff:Rip<4] now use ACTUAL max duration
- Accounts for talents that modify finisher durations
- Learns different durations per rank
- More accurate than formulas for edge cases

**Example:**
After casting Rip with 5 CP and letting it expire, system learns:
CleveRoids_ComboDurations[1079][5] = 28
Future casts use 28s instead of calculated 12+4*4

SuperCleveRoidMacros.toc

@@ -4,7 +4,7 @@
 ## Notes: /cleveroid for settings
 ## Version: 1.3
 ## OptionalDeps: ClassicFocus, FocusFrame, pfUI, SuperMacro, Bongos_ActionBar
-## SavedVariables: CleveRoidMacros, CleveRoids_LearnedDurations, CleveRoids_AuraTextures, CleveRoids_ImmunityData
+## SavedVariables: CleveRoidMacros, CleveRoids_LearnedDurations, CleveRoids_AuraTextures, CleveRoids_ImmunityData, CleveRoids_ComboDurations
 Localization.lua
 Init.lua
 Utility.lua