test: require public task examples

[c0da-ricon]

Review finding

Template's test task now models useful #USAGE example metadata, but doctor still has none and the skeleton does not protect examples as part of the public task contract. New tools can therefore copy the skeleton and add tasks whose real help offers no concrete invocation.

Fix

• add a concrete mise run doctor example;
• discover public task files in the skeleton suite;
• resolve nested/default task paths to their actual task names;
• verify every task exposes Examples: through mise run <task> --help;
• regenerate the dynamic README test count.

Validation

• focused skeleton suite: 4/4
• full default-parallel suite: 17/17
• full serial suite: 17/17
• all 8 configured lints
• README freshness, Bash syntax, and git diff --check

Fix-it for #8.