fix(ADR-0048): rescope os lint naming/namespace-prefix to intra-package duplicates (#1838)

ADR-0048 §3.4 retired the per-item cross-package collision throw, but the
naming/namespace-prefix lint rule was never updated to match. It fired on every
bare-named UI/automation item (hotcrm: 63 false positives) and claimed the
package would "collide on the registry key and fail at install" — both false.

The rule now warns only on a genuine intra-package duplicate (type, name) pair
within the linted config (the authoring-hygiene case §3.4 leaves to os lint).
Unique bare names produce zero warnings. Message no longer claims an install
failure. Runtime/registry behavior unchanged.

Co-authored-by: Jack Zhuang <277994282+os-zhuang@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: 3 people