Preserve escaped timezone directives in strftime

[OskarEichler]

Summary

Recognize %% escapes before expanding timezone directives. The current regular expression matches the second percent in %%Z, so a literal directive is replaced and then misinterpreted by Ruby's strftime.

Reproduction

For an EoTime in Asia/Kolkata:

• strftime("%%Z %%z %%:z %%::z %%/Z") now returns the literal "%Z %z %:z %::z %/Z".
• Checked mixed escaped/unescaped directives, including %%%Z and %%%%z.
• Unescaped timezone directives retain the existing library-specific formats.

Verification

• Ruby 4.0.6 via rbenv; existing Probatio suite, no test files added or modified.
• Reviewed master baseline and this individual patch each run 270 tests / 412 assertions with exactly the same three pre-existing DST/rday failures from rday / rweek calculation is odd in time zones with DST #51. Failure identities were compared, not just counts.
• A release-based 1.4.1 branch containing the five separately proposed fixes passes 263 existing tests / 405 assertions with TZInfo 2.0.6 in UTC, Asia/Tokyo, America/Chicago, Europe/Istanbul and the detected local zone.
• Temporary focused before/after reproductions pass with TZInfo 2.0.6 and 1.2.11. The combined release branch also passes the existing TZInfo 1.2.11 suite at seed 36231. Seed 99751 has the same pre-existing Zulu test-order failure on both unmodified release and patched release: a test mutates the cached TZInfo object's comparison method.
• Ruby syntax and gem packaging checks pass. Targeted Lint passes on the combined branch with the existing, unrelated AssignmentInCondition warning excluded; no lint configuration was changed.

The current master's unreleased day-delta change was not brought into the consumer branch. No live scheduler or production operations were used. Linux/Windows and other Ruby runtimes were not run locally.

Breaking changes and limitations

No intended breaking change. Escaped percent signs now follow strftime's literal-percent semantics. This does not redefine UTC formatting, timezone flag/width support, or second-resolution offsets. No overlapping current fix was found.