[Feat] Raid Frames: inverted health bars for raid and party frames

[Irame]

What does this PR do?

Adds an "Invert Health Fill" toggle to the Health Bar Fill cog on the raid
frames, next to Vertical Fill. With it on, the bar texture paints MISSING
health and current health is left to the background, so a frame reads as "how
much damage has been taken" rather than "how much health is left". Off by
default, so nothing changes for anyone who does not turn it on.

Works on both fill axes and on raid, party, extra and friendly boss frames, in
the live frames and in the options preview. The key sits in the healthBar
party-sync section, so an unsynced party tab keeps its own value.

How was it tested?

In game, on raid and party frames, with the toggle on and off:

• Both fill axes, and both combined with Vertical Fill.
• Absorb styles (overlay / blizzardModern), heal prediction, heal absorb, dead and out-of-range states.
• Party tab synced and unsynced against the raid tab.
• Options preview in every preview mode, raid and party preview.

While testing I found two seemingly unrelated bugs:

• [Bug] Raid Frames: Real preview ignores the general setting once a spec override captures it #2059
• [Bug] Raid Frames: Spec change into an override does not refresh restyle-only settings #2060

Screenshots

Before:

Raid (preview):

Party:

After:

Raid (preview):

Party:

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

Implementation note for review

This is SetReverseFill plus an inverted percent, not a swap of the two textures. The seam -- the current-HP point -- therefore stays at the same coordinate either way and only the side the fill paints on changes. That gives the rule the whole diff follows: every overlay anchored to the fill's LEADING EDGE moves from its RIGHT/TOP to its LEFT/BOTTOM, and every anchor on the health FRAME's edges is left alone. Absorb backfill and forward bars, the filled/missing clip frames, heal absorb, heal prediction and the bar background are re-anchored on that basis. SetReverseFill is owned by RF_ApplyHealthOrientation next to SetOrientation, which now returns both flags so callers take the returns instead of re-reading the setting.

The options health-animation ticker also moves from PvEffectiveProfile to the
new party-aware PvSettings, which fixes smoothBars being resolved raid-side
only in the party preview.