fix: snapshot -i auto-detects dropdown/popover interactive elements (#845)

* fix: snapshot -i auto-detects dropdown/popover interactive elements

- Auto-enable cursor-interactive scan (-C) when -i flag is used
- Add floating container detection (portals, popovers, dropdowns)
  - Detects position:fixed/absolute with high z-index
  - Recognizes data-floating-ui-portal, data-radix-* attributes
  - Recognizes role=listbox, role=menu containers
- Elements inside floating containers bypass the hasRole skip
  - Catches dropdown items missed by the accessibility tree
- Role=option/menuitem elements in floating containers captured
  even without cursor:pointer/onclick
- Tag floating container items with 'popover-child' reason
- Include role name in @c ref reasons when present
- Add dropdown.html test fixture
- Add dropdown/popover detection test suite (6 tests)
- Add test: -i alone includes cursor-interactive elements

Fixes: Bookface autocomplete, Radix UI combobox, React portals,
and similar dynamic dropdown patterns where ariaSnapshot() misses
the floating content.

* chore: bump version and changelog (v0.15.12.0)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* docs: update snapshot -i/-C flag descriptions to mention auto-enable behavior

* test: strengthen clickability test guard assertions

The @c ref clickability test previously used if-guards that would
silently pass when no Alice line was found in the snapshot output.
Both Claude and Codex adversarial review flagged this as a test that
could regress without CI noticing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* docs: regenerate top-level SKILL.md with updated flag descriptions

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: root <root@localhost>
Co-authored-by: gstack <ship@gstack.dev>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

VERSION

@@ -1 +1 @@
-0.15.11.0
+0.15.12.0