find: implement -ok and -okdir

[jmr]

-ok is like -exec ... ; but prompts the user on stderr before each invocation and only runs the command if the response is affirmative (starts with 'y' or 'Y'). -okdir is the corresponding -execdir variant. Only the ';' terminator is accepted: POSIX does not define -ok ... + and GNU find rejects it.

Response source: GNU find reads from /dev/tty so that the user's answer always comes from the real terminal even when stdin is occupied (e.g. find -files0-from - -ok rm {} \; reads paths from stdin, so responses cannot also come from there). /dev/tty is the POSIX name for a process's controlling terminal and exists on all Unix-like systems. We open /dev/tty only when stdin is itself a terminal (std::io::stdin().is_terminal() == true). When stdin is a pipe or file, we read from stdin directly — matching BSD find and making scripted use (and integration tests via pipe_in()) work naturally without any special environment variable. On Windows, or when /dev/tty cannot be opened, we likewise fall back to stdin.

Implementation: rather than a separate OkMatcher that duplicated SingleExecMatcher's fields, constructor, and exec logic, the interactive prompt is folded into SingleExecMatcher behind an interactive: bool field. SingleExecMatcher::new_interactive() constructs the -ok/-okdir variant; matches() adds a guarded block that builds a GNU-find-style prompt ("< executable arg... >? ") and calls matcher_io.confirm() before executing. If the user declines, the expression is false and the command is not run. This keeps the arg-parsing, path resolution, current_dir logic, and error handling in one place so bug fixes apply to both -exec and -ok.

Dependencies::confirm() trait method: abstracts prompt+read so matchers remain testable without a real terminal; FakeDependencies uses a VecDeque of preset responses.

Tests:

• Unit tests (exec_unit_tests.rs): confirmed executes command, declined skips command and returns false, confirmed but command fails returns false, -okdir runs in parent dir
• Parser unit tests (matchers/mod.rs): missing-arg errors, missing semicolon, correct parse, confirm/decline via FakeDependencies
• Integration tests (test_find.rs): pipe_in() makes stdin a pipe so is_terminal() returns false and responses are read from the pipe; "y"/"Y"/"yes"/" y" run command, "n" and empty response skip command, -okdir runs in parent dir, prompt format verified, missing-semicolon error

Closes #8.

[codecov]

Codecov Report

❌ Patch coverage is 89.07563% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.70%. Comparing base (5610042) to head (47e7015).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
src/find/matchers/mod.rs	87.50%	4 Missing and 3 partials ⚠️
src/find/mod.rs	76.92%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #650      +/-   ##
==========================================
- Coverage   91.76%   91.70%   -0.06%     
==========================================
  Files          31       31              
  Lines        6203     6320     +117     
  Branches      328      337       +9     
==========================================
+ Hits         5692     5796     +104     
- Misses        390      398       +8     
- Partials      121      126       +5     

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[jmr]

The code missing in the failing coverage checks looks similar to existing code where there is no failure case possible.

findutils/src/find/matchers/exec.rs

Line 46 in 1266b7f

Ok(Self {