feat: single Liquid Glass settings drawer with controllable height animation

[joeblau]

Summary

Reworks the settings sheet into a single Liquid Glass morphing drawer and adds a reusable component that gives a bottom sheet's height resize a dialable, controllable animation curve.

What changed

SettingsView

• One sheet with the system Liquid Glass chrome — glass nav bar, glass toolbar Done/back buttons, inline title (no more custom flat header painting over the glass).
• Launcher ↔ section swap with a directional push/pop slide (.move(edge:)), not a NavigationStack push.
• Height animates to fit the on-screen content, locked to the slide in one transaction.
• One light haptic per navigation (removed a duplicate).

DynamicDetentSheet.swift (new, reusable)

• DynamicDetentSheetModel + dynamicHeightDetents(_:) — animates a content-hugging .height() detent with a caller-owned curve (the reliable path for a controllable resize; the selection: form only loosely honors a curve).
• Guards the real "desync" cause: a late re-measurement restarting the spring mid-resize (isResizing + completion-based settle()).
• selectableDetents(_:selection:) for the fixed .medium/.large case.

First-open sync

• Every section's height is pre-warmed off-screen (bare Forms, no side effects), so the first open resizes in lockstep with the slide instead of a beat after it.

Verification

• Compile-verified on the iOS 27 simulator + device SDKs.
• Rendered on an iOS 27 simulator (launcher + section: glass sheet, glass toolbar buttons, correct content-fit height).
• CI builds the StreamCore test suite only (the full iOS-27 app can't build on GitHub runners); this change is UI-only and doesn't touch StreamCore.

The mic-mute FAB WIP in ContentView.swift is intentionally not in this PR — it's a separate feature.

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