Fix Doxygen gate failures on main

Four independent defects that made 'doxygen Doxyfile' exit 1:

- runtime.h: a stacked doc block above akbasic_runtime_new_function
  was left directly above akbasic_runtime_call_function's declaration
  with no function in between, so Doxygen glommed both blocks onto
  call_function and duplicated the @param obj/@param dest entries.
  Moved the block back to sit directly above new_function.
- sprite.h/akgl.h/sprite_akgl.c: three #AKGL_*/#AKBASIC_SHAPE_* Doxygen
  autolinks pointed at libakgl symbols outside this Doxyfile's INPUT,
  so they could never resolve. Converted them to plain code spans.
- scanner.c: peek(), peek_next() and match_next_char() were each
  missing @param obj (and match_next_char also cm/truetype/falsetype).
  Filled in the missing entries.
- Doxyfile: the error.h include graph hit DOT_GRAPH_MAX_NODES at
  exactly the default of 50. Raised it to 100.

Verified 'doxygen Doxyfile' now exits 0 with graphviz installed.

Refs #56

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/scanner.c

@@ -48,6 +48,7 @@ static akerr_ErrorContext *is_at_end(akbasic_Runtime *obj, bool *dest)
 
 /**
  * @brief The character under the cursor.
+ * @param obj The runtime whose scan cursor is being read.
  * @param[out] dest The character. Untouched when there is none.
  * @param[out] got  Whether there was one. The old `bool` return.
  */
@@ -70,6 +71,7 @@ static akerr_ErrorContext *peek(akbasic_Runtime *obj, char *dest, bool *got)
 
 /**
  * @brief The character one past the cursor.
+ * @param obj The runtime whose scan cursor is being read.
  * @param[out] dest The character. Untouched when there is none.
  * @param[out] got  Whether there was one. The old `bool` return.
  */
@@ -145,6 +147,10 @@ static akerr_ErrorContext *add_token(akbasic_Runtime *obj, akbasic_TokenType tok
 
 /**
  * @brief Consume one more character when it matches, choosing between two token types.
+ * @param obj The runtime whose scan cursor is being advanced.
+ * @param cm The character that must be next for the match to succeed.
+ * @param truetype The token type to report when @p cm matches.
+ * @param falsetype The token type to report when it does not.
  * @param[out] matched Whether the character was consumed. The old `bool` return.
  *
  * On the chain below `peek`, so it reports the same way. See libakstdlib #38.

src/sprite_akgl.c

@@ -875,7 +875,7 @@ static akerr_ErrorContext AKERR_NOIGNORE *run_scan(akbasic_AkglSprites *state)
  * proxy carries the owner only so a resolver can push something. Nothing here
  * resolves anything, so the field stays empty and the shape is what matters.
  *
- * Layers are the other half. A wall sits on #AKGL_COLLISION_LAYER_STATIC and
+ * Layers are the other half. A wall sits on `AKGL_COLLISION_LAYER_STATIC` and
  * responds to nothing, which is the asymmetry libakgl's masks exist for: the
  * sprite's own `collidemask` includes STATIC, so a sprite finds a wall and two
  * walls never test against each other. Sixty-four motionless rectangles