fix(checker): Tcl/iRules script bodies are reported as string literals

[dekobon]

Summary

Checker::is_string calls a Tcl / iRules braced_word a string literal
whatever role it plays, so bca find --type string reports a proc
body, an if body and an iRules when handler as string literals.

#1318 built the predicate that settles this — a braced word is a value
when the command it is passed to takes a value, and a script otherwise
— but it could not apply it here, because Checker::is_string takes
neither code nor ancestors.

Evidence

At the pinned grammars, after #1318:

$ cat p.tcl
proc p {x} { puts $x }

$ bca find --type string --no-config -p p.tcl
== p.tcl ==
╰─ {braced_word:88} from (1, 12) to (1, 23) : { puts $x }

That is a proc body — the block whose commands the walk descends into
— reported as a string literal. The literal half is already right: after
#1318 the same command reports {a b} and {c d} for
lappend x {a b} / puts {c d}, which are strings. Only the script
role is wrong.

src/checker/tcl.rs and src/checker/irules.rs both carry

impl_simple_is_string!(Tcl, QuotedWord, BracedWord, BracedWordSimple);

and BracedWord is the script kind. Alterator::alterate lists the
same three.

Why this is not a Tcl-only edit

fn is_string(node: &Node) -> bool

is the trait signature (src/checker.rs), and impl_simple_is_string!
generates it for most of the twenty-odd languages. Deciding a Tcl braced
word's role needs the source bytes (the enclosing command's leading
word) and the ancestor chain, so honouring it means widening the
signature — either by adding an is_string_with_code sibling with a
forwarding default, the shape Getter::get_op_type_with_code and
Getter::get_space_kind_with_code already use, or by widening
is_string itself and updating every impl and call site.

Note the _with_code trap in .claude/rules/grammar-dispatch.md §7:
if a sibling method is added, every call site on the walk must use the
_with_code spelling, or the override silently never fires.

Scope

• Decide between a _with_code sibling and a signature widening, and
  enumerate the call sites either way.
• Route Tcl and iRules BracedWord through the fix(getter): Tcl/iRules braced literals still fabricate a block outside special-cased commands #1318 role predicate
  (Getter::is_value_braced_word), which currently lives on Getter
  and would need to be reachable from Checker or hoisted.
• Cross-walk Alterator::alterate, which lists the same kinds
  (grammar-dispatch §7).
• Pin the answer with a bca find --type string test per dialect: a
  script body must not be reported, and the lappend x {a b} literal
  that is reported today must stay reported.

Related

• fix(getter): Tcl/iRules braced literals still fabricate a block outside special-cased commands #1318 — the Halstead half, fixed; its get_op_type arm in
  src/getter/tcl.rs carries a pointer to this issue.
• fix(getter/irules,tcl): braced words are counted as operands alongside their contents #1354, fix(getter): Tcl/iRules braced words double-count their inner words #1317, fix(getter): literal delimiters fabricate operators in eight languages #1314 — the earlier braced-word fixes.