fix(bash): track cwd across ; chains, bare cd, quoted paths, subshells

[Franky100-pig]

What

_update_cwd previously only split commands on &&, so a cd inside a
;-chained command, a quoted path with spaces, or a subshell was never
reflected in the working directory reported to the model.

How

Rewrote it with shlex(punctuation_chars=";&") plus a small
_split_statements helper, so separators inside quotes are not mistaken
for statement breaks. Now handled:

• cd a; cd b and ls x; cd a (semicolon chains)
• bare cd → home, cd to a missing dir → ignored
• quoted targets with spaces (cd "my dir")
• separators inside quotes are not treated as cd (echo "x; cd a")
• cd inside a subshell (cd a) is not tracked

Tests

Added 7 tests to tests/test_tools.py (a bash_mod fixture clears
_local.cwd). Full suite: 160 passed, including the README LoC guard.

Docs

Synced README/README_CN headline numbers (engine 1161→1191, physical
2384→2417, net 1931→1961) and the bash.py tree count (131→164).

[he-yufeng]

Thanks for this — the diagnosis was right and it held up when I ran it down on current main. The regex split misread separators inside quotes (echo "x; cd a" moved the tracked cwd) and a bare cd never went home; the quoted-path case already worked via the quote strip.

I implemented the fix fresh in 2c49e74 rather than merging this branch: same idea as yours (split on &&/; quote-aware via shlex punctuation_chars, then work on dequoted word lists), plus bare-cd-to-home and the README line-count resync the repo's badge test demands. New tests pin the quoted-separator false positive, bare cd, and a quoted target with spaces; full suite 166/166 green.

Closing this since the fix is in. Appreciate the careful writeup.