Unify P0 visual system and Live Monitor filter hierarchy

[masarray]

P0 — Visual System Unification

Presentation-only cleanup to make ARSAS read as one engineering workstation across Explorer, Live Monitor, Event Log, Alarm, GOOSE, and Diagnostics.

Scope

• Introduce one compact five-level typography contract (WorkspaceTitle, WorkspaceSubtitle, SectionTitle, BodyText, Caption, MicroLabel).
• Add shadow-free WorkspaceCard and reusable SearchSurface for main-window workspaces while leaving dialog/card styles untouched.
• Normalize dense grid typography/density for engineering scan paths.
• Unify XAML navigation and runtime SasOperationalUiPolicy styling so the visual contract does not change after Loaded; responsive MainWindowNavigationLayoutFix remains final geometry authority at 990/900/720 px.
• Remove nav font-size jitter on hover/press; use a clean internal keyboard focus ring instead of the default dotted focus visual.
• Make Global Live search the primary tool. Per-column filters now start collapsed and expand/collapse with a Filters button, while continuing to AND with global search.
• Shorten verbose workspace subtitles so the data remains the hierarchy.

Safety boundary

This PR does not modify IEC 61850 acquisition, RCB planning, SOE/event semantics, control operations, Alarm state machine, Services/*, or the ARIEC61850 engine lock. Engine remains pinned to becda399b4a3ae34831215fc915798b4f846c1be (PR #81).

Regression coverage

Adds VisualSystemP0RegressionTests and updates the existing process-value presentation wording guard to lock typography/surface tokens, stable navbar behavior, progressive Live Monitor filters, blue/slate state semantics, and the reviewed immutable engine pin.

Temporary patch tooling was removed before merge; final diff contains five presentation files plus two regression-test files.

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