Add in-game level editor with auto-discovered tile/entity palettes

Implements a full level editor that runs inside the game engine as an
alternative mode, accessible via --edit flag or E key during gameplay.
The editor auto-discovers available tiles from the tileset texture and
entities from a new central registry, so adding new game content
automatically appears in the editor without any editor-specific changes.

Editor features: tile painting (pencil/eraser/flood fill) across 3
layers, entity placement with drag-to-move, player spawn point tool,
camera pan/zoom, grid overlay, .lvl save/load, map resize, and test
play (P to play, ESC to return to editor).

Supporting changes:
- Entity registry centralizes spawn functions (replaces strcmp chain)
- Mouse input + raw keyboard access added to input system
- Camera zoom support for editor overview
- Zoom-aware rendering in tilemap, renderer, and sprite systems
- Powerup and drone sprites/animations wired up (were defined but unused)
- Bitmap font renderer for editor UI (4x6 pixel glyphs, no dependencies)

src/game/hazards.h

@@ -0,0 +1,90 @@
+#ifndef JNR_HAZARDS_H
+#define JNR_HAZARDS_H
+
+#include "engine/entity.h"
+#include "engine/camera.h"
+#include "engine/tilemap.h"
+
+/* ═══════════════════════════════════════════════════
+ *  TURRET — Wall/floor-mounted gun that shoots at
+ *  the player when in range, on a cooldown timer.
+ * ═══════════════════════════════════════════════════ */
+
+#define TURRET_WIDTH        14
+#define TURRET_HEIGHT       16
+#define TURRET_DETECT_RANGE 160.0f   /* detection radius in px       */
+#define TURRET_SHOOT_CD     2.0f     /* seconds between shots        */
+#define TURRET_HEALTH       3
+
+typedef struct TurretData {
+    float shoot_timer;               /* countdown to next shot       */
+    float fire_flash;                /* visual: time remaining on flash */
+} TurretData;
+
+void    turret_register(EntityManager *em);
+Entity *turret_spawn(EntityManager *em, Vec2 pos);
+
+/* ═══════════════════════════════════════════════════
+ *  MOVING PLATFORM — Travels back and forth along a
+ *  horizontal or vertical path. Player rides on top.
+ * ═══════════════════════════════════════════════════ */
+
+#define MPLAT_WIDTH   16
+#define MPLAT_HEIGHT  16
+#define MPLAT_SPEED   40.0f          /* pixels per second            */
+#define MPLAT_RANGE   80.0f          /* total travel distance in px  */
+
+typedef struct MovingPlatData {
+    Vec2  origin;                    /* center of travel path        */
+    Vec2  direction;                 /* (1,0) horizontal / (0,1) vert*/
+    float range;                     /* half-distance of travel      */
+    float phase;                     /* current sine phase (radians) */
+} MovingPlatData;
+
+void    mplat_register(EntityManager *em);
+Entity *mplat_spawn(EntityManager *em, Vec2 pos);
+/* Spawn with explicit direction: dir (1,0) = horizontal, (0,1) = vertical */
+Entity *mplat_spawn_dir(EntityManager *em, Vec2 pos, Vec2 dir);
+
+/* ═══════════════════════════════════════════════════
+ *  FLAME VENT — Floor-mounted grate that periodically
+ *  bursts blue flames upward. Damages on contact
+ *  when flames are active.
+ * ═══════════════════════════════════════════════════ */
+
+#define FLAME_WIDTH        16
+#define FLAME_HEIGHT       16
+#define FLAME_ON_TIME      1.5f      /* seconds flames are active    */
+#define FLAME_OFF_TIME     2.0f      /* seconds between bursts       */
+#define FLAME_DAMAGE       1
+
+typedef struct FlameVentData {
+    float timer;                     /* counts down in current phase */
+    bool  active;                    /* true = flames on             */
+    float warn_time;                 /* brief flicker before igniting*/
+} FlameVentData;
+
+void    flame_vent_register(EntityManager *em);
+Entity *flame_vent_spawn(EntityManager *em, Vec2 pos);
+
+/* ═══════════════════════════════════════════════════
+ *  FORCE FIELD — Energy barrier that toggles on/off
+ *  on a timer. Blocks movement and damages when
+ *  active, passable when off.
+ * ═══════════════════════════════════════════════════ */
+
+#define FFIELD_WIDTH       16
+#define FFIELD_HEIGHT      16
+#define FFIELD_ON_TIME     3.0f      /* seconds barrier is active    */
+#define FFIELD_OFF_TIME    2.0f      /* seconds barrier is off       */
+#define FFIELD_DAMAGE      1
+
+typedef struct ForceFieldData {
+    float timer;                     /* counts down in current phase */
+    bool  active;                    /* true = barrier is on         */
+} ForceFieldData;
+
+void    force_field_register(EntityManager *em);
+Entity *force_field_spawn(EntityManager *em, Vec2 pos);
+
+#endif /* JNR_HAZARDS_H */