#193 Migrate to signal-based inputs

[bracyw]

Changes

Migrates the entire Angular frontend from decorator-based @Input/@Output/@ViewChild/@ContentChild to signal-based input()/output()/viewChild()/contentChild() APIs. Also replaces broken ngOnChanges hooks with computed() and effect() where inputs were migrated to signals.

• Convert all @input() to input() / input.required() across ~80 components
• Convert all @output() to output()
• Convert @ViewChild/@ContentChild to viewChild()/contentChild()
• Replace ngOnChanges in BatteryLevelIndicator, StatDisplay, InfoValueDisplay, and FormTemplate with computed()/effect() since signal inputs don't trigger ngOnChanges
• Extract shared formatDisplayValue utility into pipes.utils.ts (was duplicated in stat-display and info-value-display)
• Convert get accessors to computed() in GlanceThermometer for memoization
• Simplify SwitchComponent by deriving chargingString as computed() instead of manually synced signal
• Remove dead alignment property and ngOnInit from HStackComponent
• Fix GraphDialogComponent to use plain fields instead of signal inputs (data comes from DynamicDialogConfig, not parent bindings)
• Fix FormTemplate effect to use untracked() to prevent accidental dependency tracking

Notes

• Components that receive data from DynamicDialogConfig (like GraphDialogComponent) were intentionally kept as plain class fields rather than signal inputs, since they're not bound from parent templates
• A few properties (ChargingPageMobile.time, SidebarCard.dataValue) were converted from @input to local signal() rather than input() because they were only ever set internally, never bound from a parent
• All components still have standalone: true explicitly set — removing it (since it's the Angular 19 default) is left for a follow-up to keep this PR focused on the signal migration

Test Cases

• Full Angular build passes with zero errors
• Lint passes clean across all changed files
• Prettier formatting verified on all changed .ts, .html, and .scss files
• No merge conflicts with develop

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Closes #193