feat: add :trace import tag for logging file accesses

[Koan-Bot]

Summary

Adds a :trace import tag that installs a built-in file access hook logging all unmocked file operations to STDERR. This helps developers discover which files their code touches during tests, so they know what to mock.

Fixes #9

Changes

• Add :trace (and trace) import tag that enables trace mode
• Trace hook logs [trace] open('/path') at file.pl line N to STDERR for every unmocked file operation
• Hook is installed before _strict_mode_violation so it fires even when strict mode will die
• Add :nostrict as a tag-style alias for nostrict (as suggested in the issue)
• Uses print STDERR instead of warn to avoid triggering Test2::Plugin::NoWarnings
• POD documentation for the new feature
• New test file t/trace.t covering: trace with strict, trace with nostrict, colon and non-colon syntax, caller location in output, mocked files not traced, open tracing

Test plan

• t/trace.t — tests trace output via subprocess execution (tmf_test_code) verifying STDERR output
• t/import.t — existing import tests should still pass (no behavioral change to existing tags)

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Generated by Kōan /fix

[atoomic]

Failure from CI

    # Failed test 'Exit Value Check'
    # at /home/runner/work/Test-MockFile/Test-MockFile/t/./lib/Test/TMF.pm line 87.
    # +-------+----+-------+
    # | GOT   | OP | CHECK |
    # +-------+----+-------+
    # | 65280 | eq | 0     |
    # +-------+----+-------+
    (If this table is too small, you can use the TABLE_TERM_SIZE=### env var to set a larger size, detected size is '74')

    # Command = /usr/bin/perl -I/home/runner/work/Test-MockFile/Test-MockFile/t/../lib/ /tmp/QSw4itglhG/FmGtLV9l8w
    # Exit = 65280
    # ==== Output ====
    # [trace] stat('/no/such/trace/loc_test') at /tmp/QSw4itglhG/FmGtLV9l8w line 10
    # 1..0
    # # No tests run!
    # # Seeded srand with seed '20260224' from local date.
    # 
    # ========

# Failed test 'trace output includes caller location'
# at /home/runner/work/Test-MockFile/Test-MockFile/t/./lib/Test/TMF.pm line 87.
    # Failed test 'Exit Value Check'
    # at /home/runner/work/Test-MockFile/Test-MockFile/t/./lib/Test/TMF.pm line 87.
    # +-------+----+-------+
    # | GOT   | OP | CHECK |
    # +-------+----+-------+
    # | 65280 | eq | 0     |
    # +-------+----+-------+
    (If this table is too small, you can use the TABLE_TERM_SIZE=### env var to set a larger size, detected size is '74')

    # Command = /usr/bin/perl -I/home/runner/work/Test-MockFile/Test-MockFile/t/../lib/ /tmp/QSw4itglhG/U3JKrCnepH
    # Exit = 65280
    # ==== Output ====
    # [trace] open('/no/such/trace/openfile') at /tmp/QSw4itglhG/U3JKrCnepH line 10
    # 1..0
    # # No tests run!
    # # Seeded srand with seed '20260224' from local date.
    # 
    # ========

# Failed test 'trace fires for open on unmocked files'
# at /home/runner/work/Test-MockFile/Test-MockFile/t/./lib/Test/TMF.pm line 87.
# Seeded srand with seed '20260224' from local date.
t/trace.t ........................... 
Dubious, test returned 2 (wstat 512, 0x200)
Failed 2/7 subtests 
t/unlink.t .......................... ok
t/writeline.t ....................... ok

Test Summary Report
-------------------
t/trace.t                         (Wstat: 512 (exited 2) Tests: 7 Failed: 2)
  Failed tests:  5, 7
  Non-zero exit status: 2

[atoomic]

@Koan-Bot rebase

[Koan-Bot]

Rebase: feat: add :trace import tag for logging file accesses

Branch koan.atoomic/fix-issue-9 has been rebased onto master and force-pushed.

Actions

• Read PR comments and review feedback
• Rebased koan.atoomic/fix-issue-9 onto origin/master
• Applied review feedback
• Force-pushed koan.atoomic/fix-issue-9 to origin

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