…e path

Co-authored-by: Jayson Harshbarger <Hypercubed@users.noreply.github.com>

Double-quoted tokens use the same unescapeString pipeline and per-character
pushes as single-quoted literals (no implicit 0). Add Deno compile tests and
a TAP .ffp suite under ff/lib/string/__tests__.

Co-authored-by: Jayson Harshbarger <Hypercubed@users.noreply.github.com>

Emit BRA, per-character pushes (same as single-quoted), then KET so "hi"
is a quotation; eval matches bare 'hi'. Accept standalone [ and ] tokens
so [ 'hi' ] tokenizes like the sugar form.

Update Deno IR tests, TAP tests (seq= vs [ 'hi' ], eval vs chars), and plan
implementation status.

Co-authored-by: Jayson Harshbarger <Hypercubed@users.noreply.github.com>

Go: compile "..." as BRA + per-char pushes + KET; accept [ and ] tokens.
Add compiler tests mirroring TS behavior.

Racket: lex double-quoted strings (STR-DQ), standalone [ ] (BRA/KET); share
ff-unescape with single-quoted strings. Extend brag grammar and compile/
runner/expander macros for STR-DQ and brackets.

Update string plan implementation status.

Co-authored-by: Jayson Harshbarger <Hypercubed@users.noreply.github.com>

Expand "..." at tokenize time to '[', Unicode code units as integers,
and ']', matching other compilers' BRA/push/KET shape.

- python/execute.py, ruby/execute.rb: tokenizer flat_map expansion
- dart/bin/dart.dart: tokenize() same expansion

Add small verification scripts (python test_double_quote_tokenize.py,
ruby test_double_quote_stdout.rb, dart run tool/check_double_quote.dart).
Update string plan implementation list.

Co-authored-by: Jayson Harshbarger <Hypercubed@users.noreply.github.com>

…enizer

Keep "..." as a single string token from tokenize(); prepend [ char-codes ]
to the queue when run() processes it. Update plan doc and Python self-check.

Co-authored-by: Jayson Harshbarger <Hypercubed@users.noreply.github.com>

Remove string expansion from tokenize(); handle "..." in ev() like
Python/Ruby by prepending [ code-unit tokens ] to the queue.
Update check script and plan doc.

Co-authored-by: Jayson Harshbarger <Hypercubed@users.noreply.github.com>