[YoungDan]

Summary

 destinations:
   - inventory_group: Workers
-    apps:
+    apps: []

init --provider github-token wrote a null apps: key. inventory validate requires a list, so an untouched scaffold failed with "apps must be a list". New groups and null blocks are now apps: []. Blocks that already list apps, or an inline value such as apps: [], stay as written.

Also adds one-line help for the 23 flags that rendered a blank description: --environment on the commands listed in #270, the enroll create limits, and the remediate analyse / draft filters.

Fixes #269
Fixes #270

Evidence

• Before: generated YAML contained apps: with no value, and validate_environment_yaml reported apps must be a list. --help printed those flags with an empty description.
  After: generated_scaffold_passes_environment_validator passes for a Workers scaffold. previously_blank_flags_have_one_line_help checks all 23 flags, including the enrollment defaults (500 hosts, 30 days).

cargo fmt --check, cargo clippy --all-targets --all-features -- -D warnings, and cargo test --all-features passed locally.

Merge Danger

Door: two-way

The YAML change only rewrites null apps: keys to an empty list. Authored app entries are preserved. Help text does not change parsing.

Blast Radius: init and inventory sync output for empty destinations, plus --help text.

Review from Roger or Sai (RogerLindquist, SaikrishnaGundeti). Do not merge from this change.