fix(a11y): modal accessibility — aria-modal + focus trap; consolidate on ui/Modal (destructive modals first)

[ajianaz]

Problem

Modals in the app have inconsistent accessibility. Only SettingsModal and DetailPanel are fully correct.

Modal	role=dialog	aria-modal	focus management
SettingsModal.svelte:86	✅	✅ + aria-label	❌ no focus move/trap
DetailPanel.svelte	✅	✅	❌
LifecycleView.svelte:295 (Run Cycle)	✅	❌	❌
ConsolidatePanel.svelte (Confirm Remove)	✅	❌	❌
MemoryEditor.svelte:169 (modal-overlay)	❌	❌	❌
ui/Modal.svelte (shared primitive)	❌	❌	❌ (Escape ✅)

Key gaps: keyboard Tab can escape behind the overlay on all modals; destructive-action modals (Run Cycle, Remove duplicates) are the least accessible.

There is a shared ui/Modal.svelte (Escape handling, backdrop, scale transition) but most modals don't use it — every component rolls its own.

Fix

1. Harden ui/Modal.svelte as the single modal primitive: add role="dialog", aria-modal="true", aria-label, focus-on-open (focus first focusable / Cancel button), basic focus trap (Tab/Shift+Tab cycle), restore focus on close
2. Migrate modals to it — priority order: ConsolidatePanel (destructive) → LifecycleView (destructive) → MemoryEditor → keep SettingsModal/DetailPanel markup but add focus handling

Source

Full-app UI audit (a11y; destructive flows get priority).