Standardize json.api.sh function prefix to `jq_`

[jerrod-storm]

Motivation

The current json.api.sh API uses an inconsistent naming convention:

• Most functions use a bare j prefix: jget, jset, jpush, jmap, jreduce, etc.
• Set operations use j_ with underscores: j_set_intersect, j_set_difference

Standardizing to jq_ across the board (jq_get, jq_set, jq_push, jq_map, jq_intersect, jq_difference, etc.) would:

• Make it immediately clear these are jq-backed operations
• Eliminate the mixed naming convention
• Align with the __json_api__ internal prefix convention

Scope

This is a wide-reaching mechanical rename touching:

• json.api.sh (all public function definitions)
• releases.api.sh (all call sites)
• codeberg.api.sh (all call sites)
• markdown.api.sh (all call sites)
• versions.api.sh (all call sites)
• cli/publish-release (all call sites)
• test/json.api.bats (all call sites)
• test/releases.api.bats (all call sites)
• Consumer submodules (kaitos, violet) after submodule update

Acceptance Criteria

• All public json.api.sh functions use the jq_ prefix
• All call sites updated across shellshock
• Both test suites pass
• Consumers updated after submodule bump