Require string match patterns to consume terminal newlines

[fhgffy]

Describe your changes

String patterns currently match a key ending in a newline even when the pattern does not contain that newline. For example, match("key") returns both key and key\n.

Use a strict end anchor for string patterns. Add coverage for exact keys, explicit newlines, wildcards, and compiled regex patterns.

Validation: the new regression fails before the change; all 927 tests pass with one skip after it. Ruff lint/format checks, mypy (64 source files), and wheel/sdist builds pass.

Related issue

No linked issue.

Checklist before requesting a review

• I have performed a self-review of my code.
• I have added tests for the proposed changes.
• I have run the tests and there are not errors.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.51%. Comparing base (8c3371f) to head (c15df3f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #619   +/-   ##
=======================================
  Coverage   98.51%   98.51%           
=======================================
  Files          64       64           
  Lines        2430     2430           
=======================================
  Hits         2394     2394           
  Misses         36       36           

Flag	Coverage Δ
unittests	98.51% <100.00%> (ø)

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