`find` builtin: `-path` predicate unsupported, `-not` doesn't consume its argument

[chaliy]

Summary

Two issues with the find builtin:

1. -path predicate is not recognized (find: unknown predicate '-path')
2. -not (and !) skips only itself but does not consume the following predicate+argument, causing the next token to be misinterpreted

Reproduction

# FAIL — -path not supported
mkdir -p /tmp/findtest/.git/objects
touch /tmp/findtest/file.txt
find /tmp/findtest -not -path '*/.git/*'
# expected: /tmp/findtest and /tmp/findtest/file.txt (excluding .git contents)
# actual:   find: unknown predicate '-path'

# FAIL — -not doesn't consume argument
find /tmp/findtest -not -name '*.log'
# If -not only skips itself, -name becomes a bare argument instead of a predicate

Spec tests to add

### find_path_predicate
# find -path should filter by path pattern
mkdir -p /tmp/fp_test/a/b
touch /tmp/fp_test/a/b/file.txt /tmp/fp_test/top.txt
find /tmp/fp_test -path '*/a/*' | sort
### expect
/tmp/fp_test/a/b
/tmp/fp_test/a/b/file.txt
### end

### find_not_name
# find -not -name should negate
mkdir -p /tmp/fn_test
touch /tmp/fn_test/keep.txt /tmp/fn_test/skip.log
find /tmp/fn_test -maxdepth 1 -type f -not -name '*.log' 
### expect
/tmp/fn_test/keep.txt
### end

### find_not_path_exclude
# find -not -path should exclude paths
mkdir -p /tmp/fnp_test/.git /tmp/fnp_test/src
touch /tmp/fnp_test/src/main.rs /tmp/fnp_test/.git/config
find /tmp/fnp_test -type f -not -path '*/.git/*' | sort
### expect
/tmp/fnp_test/src/main.rs
### end

Where to fix

crates/bashkit/src/builtins/ls.rs around lines 471-473:

1. Add -path predicate: Parse -path PATTERN and filter entries by matching the full path against the glob pattern.

2. Fix -not/! argument consumption: When encountering -not or !, consume the next predicate AND its arguments (e.g., -not -name '*.log' should consume both -name and '*.log'), then negate the result.

Real-world impact

The wedow/harness list_dir tool falls back to find when tree is unavailable, using find "$path" -not -path '*/.git/*' -not -path '*/node_modules/*'. Both predicates fail.