Migrate Memory surfaces to shared workspace file links

[YOMXXX]

Summary

Migrate Memory tab file affordances onto the shared workspace-link layer introduced by #2476, so memory files use the same safe open / reveal / preview contract as chat workspace links.

Problem

Issue #1402 still has one explicit acceptance criterion unmet after #2476: Memory surfaces use the shared layer. The current Memory flows in MemoryWorkspace.tsx and MemoryGraph.tsx still use bespoke Obsidian URL helpers for workspace-backed files, while #2476 covers the Tauri commands, frontend parsing, and chat markdown integration.

Without a dedicated follow-up, merging #2476 with Closes #1402 would hide the remaining Phase 3 work and leave local workspace-link behavior fragmented between chat and Memory.

Solution (optional)

• Route Memory workspace file actions through the shared workspace-link / workspace-path helpers from feat(tauri): support workspace file links #2476.
• Preserve Obsidian as an explicit action where appropriate, but avoid duplicating path normalization and local file handling logic.
• Add or reuse a small shared UI affordance for open / reveal / preview where Memory surfaces need more than one action.
• Cover MemoryWorkspace.tsx and MemoryGraph.tsx behavior with focused tests.

Acceptance criteria

• MemoryWorkspace uses shared workspace links — memory workspace file actions are routed through the shared workspace-link/path layer instead of bespoke local path handling.
• MemoryGraph uses shared workspace links — summary/file node actions use the same contract as chat workspace links.
• Obsidian behavior is preserved intentionally — Obsidian launch remains available where it is a user-facing feature, but it is composed with the shared workspace-link layer rather than replacing it.
• Open / reveal / preview behavior is tested — focused frontend tests cover Memory link routing and failure states.
• Diff coverage ≥ 80% — the implementing PR meets the changed-lines coverage gate (Vitest + cargo-llvm-cov, enforced by .github/workflows/coverage.yml).

Related

• Follow-up to Make the Tauri frontend handle workspace file links and views properly #1402 Phase 3.
• feat(tauri): support workspace file links #2476 implements the workspace path commands, parsing layer, and chat markdown integration this issue should reuse.
• app/src/components/intelligence/MemoryWorkspace.tsx
• app/src/components/intelligence/MemoryGraph.tsx