Feat/resource buff dim

[asdfractal]

What does this PR do?

• Add buff manager indicator option - frame dim. This darkens a frame when a buff is present.
• Add holy bulwark to buff list
• Add power bar buff recolour (matches resource bar implementation)

How was it tested?

Tested in raid and m+

Screenshots

Frame dim:

Power bar colour:

Checklist

• New settings default OFF (no behavior change without opt-in)
• Zero cost while disabled: no events registered, no polling, no hooks doing work, no frames built
• Cheap while enabled: event-driven (no polling, no timer-based logic, no per-frame allocations)
• No writes onto Blizzard-owned frames (weak-table pattern used); HookScript/hooksecurefunc only, never SetScript on Blizzard frames
• Tested in-game on live; no version gates or pre-Midnight APIs added