feat(cli): positional <id> args for generated commands

[ysyneu]

What

Generated OpenAPI commands were flag/--data-only (no positional args), while curated commands accept <id> [<id2>...]. That gap blocks the next stage of the generated-single-source convergence: the curated ID-based shadows (incident/alert verbs) can't be dropped without ergonomic regression.

This adds positional-argument capability to the generator. Non-breaking — it adds an optional positional onto generated commands; it removes/modifies no curated command. Foundation for a reviewed follow-up that drops the clean ID-verb shadows.

How

A generated command whose request has a required *_id (scalar) or *_ids (array) body field now accepts that id positionally. The positional is folded onto the existing flag at runtime — the flag and --data still work, with precedence --flag > positional > --data.

• Selection: required *_id/*_ids, array-wins, with a per-op override map (incident merge → target_incident_id; war-room detail/add-member → chat_id).
• Suppressed where a positional would mislead: create verbs (the required id is a parent ref like team_id, not the resource identity) and rule-move (its rule-ids field is ids, not *_ids).
• Arity: scalar → exactly one (requireExactArg); array → >=1 (requireArgs). Friendly errors mirror curated (missing X / expects exactly one X / invalid X: must be an integer).
• Types: genFoldPositional handles string scalar, string slice, int scalar (schedule_id), and intslice for []uint64 id fields (team_ids/person_ids/role_ids/…) — a naive string fold breaks genBindBody for these.

123 positionals emitted across 250 generated commands (96 scalar + 27 array, post-suppression).

Verify

• go build -tags=jsoniter ./... clean; go test -tags=jsoniter ./... all pass (incl. structural flag_consistency_test.go).
• New tests: TestSelectPositional (override / array-wins / scalar / ambiguous→none / create-suppress / empty-override) + runtime fold tests (string/slice/int/intslice/flag-overrides-positional).
• Live on testback: team infos <team-id> ([]uint64 fold) returns real data; incident info a b → expects exactly one incident_id; schedule info abc → invalid schedule_id: must be an integer; channel create --help has no positional.
• Non-breakage: only the generator, regenerated zz_generated_*, the args.go/gen_support.go shared helpers, a mechanical monit_agent.go callback-signature update, and tests — no curated command behavior changed.

Quality gates

/simplify --uncommitted (3 refactors: unused param, intermediate map, error-through-callback) + /review-to-main --uncommitted (no critical bugs; all 4 warnings + the unit-test gap folded in here).