feat: add --json/--jq/--template structured output to all view/list commands

[q-soriarty]

Cross-cutting gap

gh CLI has --json, --jq, --template flags on most list/view commands.
copia-cli has basic --json on some list commands but missing --jq and --template.

Scope

Framework-level: enhance cmdutil.AddJSONFlags to support --jq (filter) and --template (Go template).
Then apply to all list/view commands.

Commands affected

issue list/view, pr list/view, repo list/view, release list, label list,
org list/view, notification list, search repos/issues

Source: flag parity analysis