Items: hide full ammo pickups; robust close-target projection

- Resolve m_iAmmo and m_hMyWeapons arrays from the client recv tables.
- "Only if usable" now compares m_iAmmo[type] against sk_max_* (stock caps as
  fallback: RPG rockets 3, AR2 60, ...). Full ammo hides the pickup, including
  RPG rockets and fallen weapons converted to ammo.
- Inventory now comes from m_hMyWeapons directly, so fallen weapons are ammo
  before the player equips the matching weapon.
- Projection: fall back to local math when ScreenPosition claims "behind" for
  a point with positive view depth, and build NPC boxes from vertical samples
  so feet behind the near plane no longer drop the whole target. Log the first
  8 near-target projection failures for diagnosis.

1 files changed, 13 insertions, 5 deletions

diff --git a/CONTEXT.md b/CONTEXT.md
index acdab2f..839d340 100644
--- a/CONTEXT.md
+++ b/CONTEXT.md
@@ -232,7 +232,11 @@ vocabulary / decisions.
   (>1e7). A point on the view axis (e.g. directly below the player's feet)
   can make `IVDebugOverlay::ScreenPosition` return NaN/huge values; casting
   those to int corrupted the ISurface clip state and made the whole overlay
-  disappear for that frame.
+  disappear for that frame. If the overlay reports "behind" for a point whose
+  view-space depth is actually positive, a local projection is used instead.
+- NPC boxes are built from several vertical samples, so a target whose feet
+  are behind the near plane (standing over it) still gets a box from the
+  visible span instead of being dropped.
 - Projectile radius rings are drawn independently of the centre marker, so a
   grenade behind the camera/off-screen still shows its blast circle when any
   part of the ring projects.
@@ -606,10 +610,14 @@ vocabulary / decisions.
 - A world weapon whose type is already in the local player's inventory is
   reclassified as ammo (`SMG ammo`, `AR2 ammo`, ...). Owner handles are
   unreliable on this client (`m_hOwnerEntity`/`m_hOwner` resolve to -1), so
-  the inventory mask is accumulated from every weapon type the player has
-  held (client `m_hActiveWeapon`, with the server handle as fallback) since
-  the current local entity appeared. NPC-held weapons are therefore ignored.
-  Weapons the player does not own stay under the Weapons category.
+  the inventory is read directly from the local `m_hMyWeapons[48]` handle
+  array (and remembered active types as a fallback). NPC-held weapons are
+  therefore ignored. Weapons the player does not own stay under the Weapons
+  category.
+- Ammo pickups also honour "Only if usable": the reserve count from
+  `m_iAmmo[type]` is compared with the `sk_max_*` cvar (stock caps as fallback,
+  e.g. RPG rockets = 3). Full ammo hides the pickup; if either value cannot
+  be read the item stays visible.
 - Scans the client entity list every 100 ms and tags health, ammo, armor/suit,
   world weapon pickups, the two supply-crate models and generic items.
 - Each tag is a colored marker with a name and optional distance, filtered by