test: add comprehensive unit tests for Template::VMethods

[toddr-bot]

What

Add 70 unit tests for Template::VMethods, testing all 63 functions across the four vmethod groups (root, text, hash, list) plus the exported table structure.

Why

VMethods is the module behind every virtual method call in TT (item.upper, list.sort, hash.keys, etc.) — a lot of user-facing surface area with no dedicated unit tests. The existing t/vmethods/ tests exercise these through the template engine; these unit tests call functions directly and verify edge cases: mutation safety for trim/collapse, $PRIVATE pattern enforcement in hash_item, Schwartzian transform sorting with hash fields and blessed objects, splice with array replacement expansion, and match behavior with/without capture groups.

How

Direct function calls into Template::VMethods::* with Test::More subtests. No template compilation needed — pure Perl I/O verification.

Testing

• 70 subtests, all pass
• Full suite: 3456 tests, all pass

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Quality Report

Changes: 1 file changed, 614 insertions(+)

Code scan: 1 issue(s) found

• t/unit-vmethods.t:0 — 614 lines added

Tests: passed (OK)

Branch hygiene: clean

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