t27o: the oracle of regex_lite_global never samples a match, so every recorded count is 0 #11113

Goal

Make the oracle of regex_lite_global (and fns like it) exercise a match: its needle samples must include text taken from the fn's own literals, so the recorded counts are not all 0.

Why

Found by lane A4 (#11073): the sampled needles never match the sampled haystacks, so every recorded count of regex_lite_global is 0 and the oracle test asserts only the empty case. A test that can only see 0 cannot tell a correct conversion from a broken one. The sampled needle "" also made the first harness loop forever (guarded since #11109).

Boundary

• specs/tools/t27o/rust_convert.t27
• gen/rust/tools/t27o/rust_convert.rs
• .trinity/seals/t27o_T27oRust.json

User Scenarios

• Given a fn taking a haystack and a needle as text, when t27o writes its oracle, then at least one sample pair has the needle inside the haystack.
• Given a fn whose literals include a word, when the oracle samples text, then that word is one of the samples.

Requirements

• FR-001: Text samples MUST include each string literal of the fn body, and a sample that contains it.
• FR-002: The sampler MUST keep its bound: no sample may run longer than the harness guard allows.

Success Criteria

• The oracle of regex_lite_global records at least 1 non-zero count over its samples.
• t27b test specs/tools/t27o/rust_convert.t27 ends with exit 0 and 0 tests failing, and t27c test-report reports 0 vacuous passes.