fix(strata): render overlaid elements above their borders

[nulltyto]

Summary

Fixes a class of layering bug where overlaid elements rendered beneath their frame's border (or below the bars) because they sat at a lower frame level / strata than the overlapping border. Each is raised above its border (or, where the border should win, ordered deliberately).

Bug reports

• https://discord.com/channels/585577383847788554/1518307676893876344
• https://discord.com/channels/585577383847788554/1518302204509950014

Fixes

• DK rune cooldown number — countdown text now clears the outer bar border. (Rune pips use per-pip border size 0, so the visible border is secondaryFrame._barBorder at +5; the number was below it.)
• Role icon & leader/assist crown (party/raid) — moved into the above-border/below-aura band (LVL_AURA - 1) in both the real and preview builders, so they clear the general border while auras still draw over them and the hover/target border raise still covers them. The leader crown was also taken off the chat strata on real frames (it was a lower strata than the frame, so it always drew under the border).
• Group numbers (raid) — hosted on a high-level overlay so they draw over the bars instead of behind them (real + preview).
• Targeted spells (party) — the spell icon and its border now sit below the health-text carrier so the health % stays readable when the icon is centered over it (border still above the icon).
• Tracking bars — timer/name/stacks text overlay raised above the bar border (and pandemic glow). The options preview also gains vertical headroom so text positioned above/below the bar is no longer clipped by the scroll wrapper.
• Damage meters — bar position/name/amount text raised above the lazily-created bar border.

Notes

• Layering-only changes (frame level / strata / parent / draw order) — no behavioral or secure-frame changes, so they're combat-safe.
• Verified in-client: runes, role/leader icons (live + preview), group numbers (live + preview), targeted spells, tracking bars + options preview, and damage meters with borders enabled.