docs: Update C++ integration guide and blueprint specifications for various systems, adding detailed setup instructions and clarifying implementation statuses

docs/blueprints/02-player/09_BPC_StaminaSystem.md

@@ -1,5 +1,9 @@
 # 09 — Stamina System (`BPC_StaminaSystem`)
 
+> **⚡ C++ Status: Stub** — `Source/PG_Framework/Public/Player/BPC_StaminaSystem.h` provides the UCLASS shell, `MaxStamina`/`CurrentStamina` variables, and `OnExhaustionStateChanged` dispatcher. **The C++ stub has NO gameplay logic.** **Create a BP child** and build ALL logic: sprint drain, action costs, exhaustion state machine, regen delay + rate, `CanAffordAction(Cost)` query. See `docs/developer/cpp-integration-guide.md`.
+>
+> ---
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 ## Purpose
 Manages the player's stamina pool — drain during sprinting, jumping, and special actions; regeneration during idle/walking. Prevents action spamming by enforcing minimum stamina thresholds. Drives exhaustion VFX and audio cues.