feat(core): INCLUDE, error overhaul, sf64 lane, WORDS ALL, .RS

WS-012 -- INCLUDE/INCLUDED:
- Injected source loader (core stays IO-free: CLI installs a
  filesystem reader, web leaves it unset -> defined error). Recursive
  include_file feeds files line-by-line through evaluate, so compile
  state and SEE capture span lines for free. Cycle detection, depth
  cap 16, paths relative to the including file, SOURCE-ID per nesting
  level, parent input restored on success/error/BYE.
- CLI file mode now runs through the include machinery: `wafer x.fth`
  gets file:line error context and a base dir for nested INCLUDEs.
- Unlocks the REMEMBER+INCLUDE reload loop.

WS-008 -- error reporting remainder:
- Errors inside included files carry `file.fth:12:` context
  (anyhow context chain; CLI prints {e:#}).
- describe_uncaught now returns typed WaferError::UncaughtThrow
  { code, message } -- display text unchanged, THROW code reachable
  via downcast for CLI/web consumers.
- compile_word emits a WASM name section; wasmtime trap backtraces
  name the faulting word and runtime_native prefixes "in <WORD>:".
  Batch/consolidated modules stay unnamed (no name plumbing there;
  boot primitives rarely trap).

WS-003 -- SwiftForth correctness lane:
- compare_all_programs_sf64 runs the program corpus with sf64 as
  oracle; whitespace-token comparison (sf64 prints numbers
  space-prefixed and echoes piped lines). 34/35 parity; dot-quote
  skipped (interpret-mode ." is a SwiftForth no-op). #[ignore]d like
  the gforth lane; `just compare-correctness` runs both.

WS-011 leftovers:
- WORDS ALL: grouped full view -- one section per wordlist (search
  order first), then internal words, each with counts. Backed by
  Dictionary::visible_entries (name, wid, internal); visible_words
  now derives from it.
- .RS / RDEPTH: return-stack introspection in boot.fth over a new
  RP@ primitive (IrOp::RpFetch); BEGIN/WHILE walk so the walk never
  touches the stack it prints. SPACES clamped per 6.1.2230.

549 unit + 11 compliance + 9(+2) comparison + 5 crypto + 1 bench
green; fmt/clippy clean; --no-default-features and wasm32 web checks
pass.

crates/core/src/wordhelp.rs

@@ -124,6 +124,8 @@ pub const WORD_DOCS: &[(&str, &str, &str)] = &[
         "Move back items stored by N>R.",
     ),
     ("SP@", "( -- addr )", "Current data-stack pointer."),
+    ("RP@", "( -- addr )", "Current return-stack pointer."),
+    ("RDEPTH", "( -- n )", "Number of cells on the return stack."),
     // -- Core: arithmetic --
     ("+", "( n1 n2 -- n3 )", "Add: n3 = n1 + n2."),
     ("-", "( n1 n2 -- n3 )", "Subtract: n3 = n1 - n2."),
@@ -1003,7 +1005,7 @@ pub const WORD_DOCS: &[(&str, &str, &str)] = &[
     (
         "WORDS",
         "( \"filter\"? -- )",
-        "List visible words; optional substring filter.",
+        "List words; optional substring filter; ALL = grouped view.",
     ),
     (
         "SEE",
@@ -1022,6 +1024,7 @@ pub const WORD_DOCS: &[(&str, &str, &str)] = &[
     ),
     (".S", "( -- )", "Print the data stack, respecting BASE."),
     ("F.S", "( -- )", "Print the float stack."),
+    (".RS", "( -- )", "Print the return stack, respecting BASE."),
     ("?", "( addr -- )", "Fetch and print the cell at addr."),
     (
         "DUMP",
@@ -1048,6 +1051,16 @@ pub const WORD_DOCS: &[(&str, &str, &str)] = &[
         "( -- )",
         "Make the current state the EMPTY baseline.",
     ),
+    (
+        "INCLUDED",
+        "( c-addr u -- )",
+        "Interpret the named source file (nestable).",
+    ),
+    (
+        "INCLUDE",
+        "( \"name\" -- )",
+        "Interpret the source file named in the input.",
+    ),
     // -- WAFER-specific --
     (
         "CONSOLIDATE",