proof/: add physics diagnostic/benchmark/pipelining coverage

StarForth_Physics_Diagnostic_Words.thy (physics_diagnostic_words.c):
3 of 4 words are pure-printf identity transitions; PHYSICS-BURN's guard
modelled, its arbitrary dynamically-selected func-pointer execution loop
is a new class of gap (not reducible to any prior one).

StarForth_Physics_Benchmark_Words.thy (physics_benchmark_words.c):
hot-words cache is a whole unmodelled subsystem. PHYSICS-RESET-STATS's
pipeline_metrics half (3 real vm_state fields) modelled; everything else
in the file deferred.

StarForth_Physics_Pipelining_Diagnostic_Words.thy
(physics_pipelining_diagnostic_words.c): root-cause finding --
`word_transition_metrics` has been a declared record type in
StarForth_Base.thy since early in the sweep but was never wired into
`dict_entry` as a field, so every word in this file touches state with
zero abstract representation. Three no-arg words modelled as identity
(with an explicit caveat that this reflects the model's blind spot, not
a no-op claim about the C); the three lookup words get only their
simplest empty-stack underflow case.

Suite now 43 theories, green.

proof/StarForth_Physics_Diagnostic_Words.thy

@@ -0,0 +1,102 @@
+theory StarForth_Physics_Diagnostic_Words
+  imports StarForth_Base
+begin
+
+(* =========================================================================
+   Mirrors: src/word_source/physics_diagnostic_words.c
+   Registers: PHYSICS-WORD-METRICS PHYSICS-CALC-KNOBS PHYSICS-BURN
+              PHYSICS-SHOW-FEEDBACK
+
+   Interactive stdout demonstrations of the Loop #1 physics feedback loop,
+   built for REPL walkthroughs, not for programmatic use.
+
+   ── Scope ─────────────────────────────────────────────────────────────
+   PHYSICS-WORD-METRICS, PHYSICS-CALC-KNOBS, and PHYSICS-SHOW-FEEDBACK are
+   fully modelled: all three share the identical structure of "find the
+   dictionary entry with the largest `physics.last_active_ns` (a linked-
+   list scan via ->link, the same class of raw traversal already flagged
+   not-modelled for FORGET/ALL-HEATS -- but note this scan is READ-ONLY,
+   selecting which entry to print, with no consequence for what state
+   ends up being characterised), then printf a derived report from its
+   fields (`float` thermal-pressure math, purely for display -- not stored
+   anywhere)". None of the three writes to a SINGLE field of `vm_state` or
+   any `dict_entry` -- their entire observable contract, independent of
+   the (unmodelled) linked-list scan, is "no state change". Modelled as
+   identity transitions.
+
+   PHYSICS-BURN is different: its guard conditions are modelled, but its
+   core effect -- calling `target->func(vm)` in a loop, where `target` is
+   whichever word the same last-active-ns scan selects -- is NOT. This is
+   a genuinely new kind of gap for this sweep: every other file's
+   unmodelled dispatch has been either DEFER-style reassignment (function
+   pointer stored then later read) or a call embedded in a fixed
+   C-language control path (DODOES). PHYSICS-BURN calls an ARBITRARY,
+   data-dependent word's `func` directly from within a diagnostic
+   primitive -- there is no way to characterise its effect without first
+   knowing (a) which word gets selected (the unmodelled scan) and (b) what
+   that word's `func` does (the `word_table`/`word_physics_transparent`
+   abstraction StarForth_Transition.thy already provides IS the right tool
+   for word execution in general, but PHYSICS-BURN's selection is dynamic
+   and data-dependent in a way no other call site in this suite is).
+   ======================================================================== *)
+
+(* ── PHYSICS-WORD-METRICS / PHYSICS-CALC-KNOBS / PHYSICS-SHOW-FEEDBACK ────
+   All three: ( -- ), stdout-only, no vm_state field written. *)
+
+definition forth_physics_word_metrics :: "vm_state \<Rightarrow> vm_state" where
+  "forth_physics_word_metrics vm = vm"
+
+definition forth_physics_calc_knobs :: "vm_state \<Rightarrow> vm_state" where
+  "forth_physics_calc_knobs vm = vm"
+
+definition forth_physics_show_feedback :: "vm_state \<Rightarrow> vm_state" where
+  "forth_physics_show_feedback vm = vm"
+
+lemma physics_word_metrics_identity:
+  "forth_physics_word_metrics vm = vm"
+  by (simp add: forth_physics_word_metrics_def)
+
+lemma physics_calc_knobs_identity:
+  "forth_physics_calc_knobs vm = vm"
+  by (simp add: forth_physics_calc_knobs_def)
+
+lemma physics_show_feedback_identity:
+  "forth_physics_show_feedback vm = vm"
+  by (simp add: forth_physics_show_feedback_def)
+
+(* ── PHYSICS-BURN ( n -- ) : guards only ──────────────────────────────── *)
+(* C: error if stack empty; pop burn_count; if burn_count < 1, printf and
+   return (no-op beyond the pop); otherwise scans for a target word (same
+   unmodelled last-active-ns scan as the three words above) and calls its
+   func burn_count times -- NOT modelled, see file header. *)
+
+definition forth_physics_burn_guard :: "vm_state \<Rightarrow> vm_state" where
+  "forth_physics_burn_guard vm =
+    (case data_stack vm of
+       []     \<Rightarrow> set_error vm
+     | n # xs \<Rightarrow> vm\<lparr>data_stack := xs\<rparr>)"
+
+lemma physics_burn_underflow:
+  assumes "data_stack vm = []"
+  shows "vm_error (forth_physics_burn_guard vm)"
+  by (simp add: forth_physics_burn_guard_def set_error_def assms)
+
+lemma physics_burn_pops_one:
+  assumes "data_stack vm = n # xs"
+  shows "data_stack (forth_physics_burn_guard vm) = xs"
+  by (simp add: forth_physics_burn_guard_def assms)
+
+lemma physics_burn_nonpositive_count_is_pop_only: True
+  \<comment> \<open>C: `if (burn_count < 1) { printf(...); return; }` -- once the
+     underflow guard passes and burn_count < 1, the word's entire
+     remaining effect is the pop already captured by
+     forth_physics_burn_guard.\<close>
+  by simp
+
+lemma physics_burn_loop_not_modelled: True
+  \<comment> \<open>burn_count \<ge> 1: repeatedly calls an arbitrary, dynamically-selected
+     word's `func` pointer -- see file header for why this is a new class
+     of gap, not reducible to any single already-flagged one.\<close>
+  by simp
+
+end