fix: reduce questie fps stutter hot paths

CHANGELOG.md

@@ -41,6 +41,7 @@
 
 ### Bug Fixes
 
+- **[Performance - Minimap Filter And Learner Kill Hot Paths]** (#20) Reduced two likely stutter sources introduced after 1.6.2: minimap fade passes now cache expensive quest-filter visibility checks for already-visible icons instead of re-running them every 0.1s per icon, while still forcing a fresh check before hidden icons reappear; and the learner kill path no longer runs the spawn-evidence merge scan before the merger's three-evidence minimum can succeed.
 - **[Map Tooltip - Objective Progress Refresh]** (#18) Minimap and world-map objective pin tooltips now refresh the underlying objective before rendering progress text, so kill counters update on hover instead of staying at the count captured when the pin was drawn.
 - **[Learner - Stop Recording Bystander Kills As Your Own]** Kills of mobs you never engaged (other players killing nearby mobs) were being recorded as spawns at *your* position and inflating the kill count. The combat-log handler passed `px,py=nil` to `LearnNPC` for uncredited kills, whose `GetPlayerCoords` fallback then stored your location as the mob's spawn. Spawn recording (`LearnNPC` + GUID evidence) is now gated on a captured position, so only credited kills (your own / party kills you engaged, where a real position was captured) store a spawn. Bystander kills no longer pollute the learner with your coordinates or inflate the count; the NPC's name/quest data is still learned via mouseover/target.
 - **[Fix - Fade Pass Crash On Stale Frame]** Hardened `ShowQuestIcons`/`HideQuestIcons` against a stale-frame desync (`attempt to index local 'icon'`): a frame name lingering in the registry after its frame was reset is now skipped gracefully instead of erroring out of the whole fade pass (and `ShowQuestIcons` no longer `error()`s on the desync), with nil-guards on `icon`/`icon.data`/`icon.data.QuestData`.