fix(cli): unshadow -y / -f flags and JSON contract for action-less nodes (#370, #421, #422)

[PeterGuy326]

Summary

Fixes three CLI-side flag/output bugs, all verified by build + manual run + unit tests on a fresh open build (v1.0.35 baseline).

#370 — -y shorthand shadowed on todo task delete / skill setup

Both commands registered a local --yes flag without the -y shorthand, shadowing the global persistent -y/--yes. Result: dws todo task delete -y and dws skill setup -y failed with unknown shorthand flag: 'y'.

Fix: Bool("yes", ...) → BoolP("yes", "y", ...), matching the already-correct drive delete pattern.

# before: {"error":{"message":"unknown shorthand flag: 'y' in -y"}}
# after:
$ dws todo task delete -y
{"error":{"category":"validation","message":"--task-id is required"}}   # -y parsed
$ dws todo task delete --help   # shows: -y, --yes

#421 — local --format shadows global -f/--format on aitable export data

aitable export data registered a local --format (export format) with the same long name as the global persistent output flag, dropping the -f shorthand on this command (unknown shorthand flag: 'f').

Fix: rename the export flag to --export-format (aligns with doc.go's existing --export-format). The MCP request param key stays "format"; help/examples/tests updated.

# before: dws aitable export data -f json -> unknown shorthand flag: 'f'
# after:
$ dws aitable export data -f json
{"error":{"category":"validation","message":"--base-id is required"}}   # -f works

#422 — action-less group nodes print usage text under -f json

A group node with no tool of its own (e.g. chat group member-role) printed human usage text even when -f json was requested, breaking JSON-only agent/MCP consumers.

Fix: NewGroupCommand now returns a structured validation error (naming the available subcommands) when the user explicitly selects json/ndjson (checked via Changed("format"), mirroring upgrade.go); a bare invocation still shows help, so human discovery UX is unchanged.

$ dws chat group member-role -f json
{"error":{"category":"validation","message":"\"dws chat group member-role\" requires a subcommand"}}
$ dws chat group -f json
{"error":{"category":"validation","message":"... requires a subcommand; available: bots, create, dismiss, ..."}}
$ dws chat group member-role          # no -f -> still prints help

Out of scope

chat group member-role being an empty shell (its list/add/update/remove tools are orphaned under group name group-role vs the declared member-role in discovery config) is a separate discovery-config issue and will be handled via the discovery release flow, not this code PR.

Testing

• go build ./... ✓
• go vet ./internal/... ✓
• go test ./internal/cobracmd/... ./internal/compat/... ./internal/helpers/... ✓
• Manual runs as shown above on a local open build.