Namespace every exported symbol, and bump to 0.5.0

Closes internal-consistency items 1 through 6, 12 and 13. Every include guard
is _AKGL_<FILE>_H_, every in-project header include is angled, and every
exported function, type and global carries the akgl_ prefix. This is an ABI
break; the soname goes to libakgl.so.0.5. TODO.md carries the full rename
table.

The renames were driven by renaming each declaration and letting the compiler
find the uses, not by pattern substitution: renderer, physics and camera are
also parameter and struct-member names, and a sed would have rewritten
map->physics and every akgl_RenderBackend *renderer parameter without a word.

Item 4 turned out not to be cosmetic. The library exported a global called
renderer and tests/character.c defined an SDL_Renderer *renderer of its own;
the executable's definition preempted the library's, akgl_sprite_load_json
read a SDL_Renderer * through an akgl_RenderBackend *, and every texture load
in that suite failed. The suite reported success anyway, because libakerror's
unhandled-error handler ends in exit(errctx->status), exit keeps only the low
byte, and AKGL_ERR_SDL is exactly 256. So character had been green while
running one of its four tests, and every suite in the tree was unable to fail
on the most common status in a library built on SDL.

Both are fixed. tests/testutil.h gains TEST_TRAP_UNHANDLED_ERRORS(), which
collapses any status a byte cannot carry onto 1, and every suite installs it.
character binds a real backend with akgl_render_2d_bind. Its fourth test then
runs for the first time and fails on a defect it has asserted all along, so
akgl_heap_release_character now walks state_sprites with
AKGL_ITERATOR_OP_RELEASE and destroys the property set before zeroing the slot
-- TODO.md Defects item 21 and half of Carried over item 1.

AKGL_TIME_ONESEC_MS said "one second in milliseconds" and held 1000000, so
akgl_game_state_lock waited roughly sixteen minutes rather than one second. It
is AKGL_TIME_ONEMS_NS now, the budget is its own named constant, and
tests/game.c holds the mutex from a second thread to assert the wait -- the
contended path had no coverage at all.

Headers are self-contained and it is enforced: AKGL_PUBLIC_HEADERS drives both
install() and a generated translation unit per header, so a header that ships
is a header that is checked. Writing that found registry.h, which used
SDL_PropertiesID in eight declarations and included no SDL header.

23/23 suites pass, memcheck is clean, reindent --check is clean.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

include/akgl/controller.h

@@ -24,12 +24,12 @@
  * akgl_controller_poll_keystroke().
  */
 
-#ifndef _CONTROLLER_H_
-#define _CONTROLLER_H_
+#ifndef _AKGL_CONTROLLER_H_
+#define _AKGL_CONTROLLER_H_
 
 #include <SDL3/SDL.h>
 #include <akerror.h>
-#include "types.h"
+#include <akgl/types.h>
 // The binding handlers below take an akgl_Actor *, so this header cannot be
 // included before akgl/actor.h without one. akgl_Actor is a typedef of a named
 // struct, and repeating a typedef is not C99, so it is included rather than
@@ -94,7 +94,7 @@ typedef struct {
 } akgl_ControlMap;
 
 /** @brief Every control map. Zeroed by akgl_game_init; index it by the same id the functions below take. */
-extern akgl_ControlMap GAME_ControlMaps[AKGL_MAX_CONTROL_MAPS];
+extern akgl_ControlMap akgl_controlmaps[AKGL_MAX_CONTROL_MAPS];
 
 /**
  * @brief Log every attached keyboard and its SDL id.
@@ -190,7 +190,7 @@ akerr_ErrorContext AKERR_NOIGNORE *akgl_controller_handle_removed(void *appstate
  * The binding is copied, so the caller's `akgl_Control` can be a stack local
  * reused across pushes -- which is exactly what akgl_controller_default does.
  * Bindings can only be appended; there is no remove, and no way to reset a map
- * short of zeroing it in ::GAME_ControlMaps directly.
+ * short of zeroing it in ::akgl_controlmaps directly.
  *
  * @param controlmapid Which map to append to, 0 through
  *                     #AKGL_MAX_CONTROL_MAPS - 1.
@@ -203,7 +203,7 @@ akerr_ErrorContext AKERR_NOIGNORE *akgl_controller_handle_removed(void *appstate
  *
  * @warning A **negative** @p controlmapid is not rejected -- only the upper
  *          bound is checked -- and indexes before the start of
- *          ::GAME_ControlMaps. TODO.md, "Known and still open" item 11.
+ *          ::akgl_controlmaps. TODO.md, "Known and still open" item 11.
  */
 akerr_ErrorContext AKERR_NOIGNORE *akgl_controller_pushmap(int controlmapid, akgl_Control *control);
 
@@ -212,7 +212,7 @@ akerr_ErrorContext AKERR_NOIGNORE *akgl_controller_pushmap(int controlmapid, akg
  *
  * Points the map at the named actor and pushes eight bindings: the four arrow
  * keys and the four D-pad directions, each wired to the matching
- * `akgl_Actor_cmhf_*_on`/`_off` pair. It is the "just give me something that
+ * `akgl_actor_cmhf_*_on`/`_off` pair. It is the "just give me something that
  * works" path -- a game wanting different keys builds its own bindings with
  * akgl_controller_pushmap.
  *
@@ -334,4 +334,4 @@ akerr_ErrorContext AKERR_NOIGNORE *akgl_controller_poll_keystroke(akgl_Keystroke
  * @return `NULL`. There is no failure path -- it resets two counters.
  */
 akerr_ErrorContext AKERR_NOIGNORE *akgl_controller_flush_keys(void);
-#endif // _CONTROLLER_H_
+#endif // _AKGL_CONTROLLER_H_