Remove dark box-shadow halo, make cards theme-aware

The active speech form had a hardcoded dark box-shadow that appeared as a halo in light theme. Since the ::after top-edge highlight already signals the active state, the shadow was removed entirely. A full audit of frontend box-shadows revealed two other elements with the same pattern: .perm-card and .api-key-dialog__content. These now use theme-aware shadows — strong in dark mode, soft in light mode — preserving their lift effect.

• Removed hardcoded dark box-shadow from .speech-form–active (no light override)

• Audited all frontend box-shadows for hardcoded-dark pattern

• Made .perm-card and .api-key-dialog__content theme-aware: strong shadow in dark, soft shadow in light

• Co-authored with Claude Opus 4.7