starkernel: item 3.1 reopened -- two Kconfig symbols items 1.1/1.4 deferred here

Punch list §25 item 3.1 re-closed after reopening.

Items 1.1 and 1.4's resolutions both explicitly named this item as
where their Kconfig symbols would be implemented, but 3.1's own stated
scope never mentioned them, so the first close missed both:

- STADIUM_CONTAINS_DEPTH_MAX (default 5) -- item 1.1's contains-chain
  depth cap. No consumer yet; reap-gating enforcement is item 3.5.
- STADIUM_CAPACITY_TICK (default 1000) -- item 1.4's capacity
  arbitration cadence in virtual ticks. No consumer yet; capacity
  arbitration itself is not on the punch list.

Both added following STADIUM_MAX_VM_COUNT's exact pattern:
Kconfig.kernel entry, Makefile.starkernel kconfig_int +
VM_FEATURE_FLAG_VARS forwarding, starforth_config.h fallback default.
stadium.h now includes starforth_config.h and carries two more
C99-portable compile-time checks proving both symbols are defined and
sane, same discipline as the byte-count checks. Declaration only --
not inventing the consuming logic to close this out early.

Verified: three-architecture boot (amd64, aarch64, riscv64), all
reaching ok> with identical dict_hash=0x3d4e1daf289da94f, re-run after
the reopening.

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

include/starforth_config.h

@@ -71,6 +71,8 @@
 #define STARFORTH_CONFIG_HEARTBEAT_TICK_NS_DEFAULT 10000ULL
 #define STARFORTH_CONFIG_HEARTBEAT_INFERENCE_FREQUENCY_DEFAULT 1000
 #define STARFORTH_CONFIG_STADIUM_MAX_VM_COUNT_DEFAULT 4
+#define STARFORTH_CONFIG_STADIUM_CONTAINS_DEPTH_MAX_DEFAULT 5
+#define STARFORTH_CONFIG_STADIUM_CAPACITY_TICK_DEFAULT 1000
 #define STARFORTH_CONFIG_HEARTBEAT_CHECK_FREQUENCY_DEFAULT 256
 #define STARFORTH_CONFIG_HEARTBEAT_WINDOW_TUNING_FREQUENCY_DEFAULT 1000
 #define STARFORTH_CONFIG_HEARTBEAT_SLOPE_VALIDATION_FREQUENCY_DEFAULT 5000
@@ -160,6 +162,14 @@
 #define STADIUM_MAX_VM_COUNT STARFORTH_CONFIG_STADIUM_MAX_VM_COUNT_DEFAULT
 #endif
 
+#ifndef STADIUM_CONTAINS_DEPTH_MAX
+#define STADIUM_CONTAINS_DEPTH_MAX STARFORTH_CONFIG_STADIUM_CONTAINS_DEPTH_MAX_DEFAULT
+#endif
+
+#ifndef STADIUM_CAPACITY_TICK
+#define STADIUM_CAPACITY_TICK STARFORTH_CONFIG_STADIUM_CAPACITY_TICK_DEFAULT
+#endif
+
 #ifndef HEARTBEAT_CHECK_FREQUENCY
 #define HEARTBEAT_CHECK_FREQUENCY STARFORTH_CONFIG_HEARTBEAT_CHECK_FREQUENCY_DEFAULT
 #endif

include/starkernel/vm/stadium.h

@@ -35,6 +35,7 @@
 #ifdef __STARKERNEL__
 
 #include <stdint.h>
+#include "starforth_config.h" /* STADIUM_CONTAINS_DEPTH_MAX, STADIUM_CAPACITY_TICK */
 
 #define STADIUM_CELL_BYTES 64
 
@@ -56,7 +57,9 @@ typedef struct {
     uint64_t heat;         /* offset 8  -- Q48.16, conserved share of 1.0 (§19.1) */
     uint32_t ttl;          /* offset 16 -- remaining lifetime; messages and ACLs only (§17.1) */
     uint32_t link;         /* offset 20 -- index into the Stadium, not a pointer */
-    uint32_t contains;     /* offset 24 -- index of the patron held inside this one, or none (item 1.1) */
+    uint32_t contains;     /* offset 24 -- index of the patron held inside this one, or none (item 1.1).
+                             * Chains up to STADIUM_CONTAINS_DEPTH_MAX deep; reap-gating
+                             * enforcement of that bound is item 3.5's scope, not this one's. */
     uint16_t mass;         /* offset 28 -- cells this patron occupies (§19.2) */
     uint8_t  flags;        /* offset 30 -- bit 0 = pin; remaining bits reserved */
     uint8_t  behaviour;    /* offset 31 -- code field, closed enumeration (§18.3) */
@@ -90,6 +93,16 @@ typedef char stadium_header_size_check[(sizeof(StadiumPatronHeader) == STADIUM_C
 typedef char stadium_continuation_size_check[(sizeof(StadiumContinuationCell) == STADIUM_CELL_BYTES) ? 1 : -1];
 typedef char stadium_cell_size_check[(sizeof(StadiumCell) == STADIUM_CELL_BYTES) ? 1 : -1];
 
+/*
+ * Items 1.1 and 1.4 named this item as where their Kconfig symbols would be
+ * implemented. Neither has a consumer yet (item 3.5 for the depth cap,
+ * capacity arbitration -- not yet on the punch list -- for the tick); these
+ * checks only prove the symbols are defined and sane, the same discipline
+ * already applied to the byte-count checks above.
+ */
+typedef char stadium_contains_depth_configured_check[(STADIUM_CONTAINS_DEPTH_MAX > 0) ? 1 : -1];
+typedef char stadium_capacity_tick_configured_check[(STADIUM_CAPACITY_TICK > 0) ? 1 : -1];
+
 #endif /* __STARKERNEL__ */
 
 #endif /* STARKERNEL_VM_STADIUM_H */