Stage MC-0c: shared VM code made per-VM or atomic (FABRIC-3.10.8 §3.4)

- Dictionary lookup index is per VM (vm->fc_index, struct SfFcIndex):
  was one global index rebuilt whenever a different VM was searched, and
  heat reorganization could reorder another VM's buckets. Allocated on
  first lookup, freed by vm_cleanup(); allocation failure counted/logged,
  lookup falls back to a newest-first dictionary walk.
- PRNG: still one stream, stepped by compare-and-swap; SEED one store.
- state_variable removed (write-only; STATE is vm->mode).
- Sweep additions (Captain Bob's ruling): heartbeat_export.c delta
  last-values moved into each VM's HeartbeatState (were statics shared by
  every VM -- wrong across VMs today); TOP-WORDS list heap-sized per call
  (was static [1000]); inference_outputs_to_string() takes a caller
  buffer; three failure counters atomic; crc64 table published with
  release/acquire.
- Confirmed, unchanged: g_runtime compiled out of the kernel,
  g_hotwords_cache unreferenced, ttf cache core-0-only.
- Probe (removed): every VM has its own index; two VMs searched
  alternately 2x5000 lookups: 0 rebuilds, 0 wrong-VM results, all three
  ISAs.
- Standard sequence on amd64/aarch64/riscv64: dict_hash set unchanged,
  G byte-identical, MINT/WIREBIND/USE ok, conservation true, 0 idle growth.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

include/vm.h

@@ -312,6 +312,13 @@ typedef struct
     uint64_t run_start_ns;                  /* Monotonic time at run start */
     uint32_t tick_number_offset;            /* Tick counter for this run */
 
+    /* heartbeat_capture_tick_snapshot()'s previous values, for its deltas
+     * (FABRIC-3.10.8 MC-0c: were function-local statics shared by every VM,
+     * so each VM's delta was taken against whichever VM was sampled last). */
+    uint64_t export_last_tick_count;
+    uint64_t export_last_words_executed;
+    uint64_t export_last_early_exit_count;
+
     /* === L8 Attractor Bucket Statistics === */
     double bucket_sum_K;                    /* Sum of K values across bucket */
     double bucket_sum_K_squared;            /* Sum of K^2 for variance calculation */
@@ -594,6 +601,9 @@ typedef struct VM
      * @{
      */
     HotwordsCache* hotwords_cache; /**< Frequency-driven dictionary acceleration cache */
+    struct SfFcIndex *fc_index;    /**< This VM's first-character lookup index
+                                    *   (FABRIC-3.10.8 MC-0c; dictionary_management.c,
+                                    *   allocated on first lookup, freed by vm_cleanup()) */
     /** @} */
 
     /** @name Rolling Window of Truth (Deterministic Metrics)