Route work-product clicks through a resolver IPC

Filesystem work products store `external_id` as a workspace-relative
path so artifacts survive a workspace-root move, but the renderer was
handing that relative fragment straight to `shell.openPath`, which
needs an absolute managed path. Clicks flickered into a failed open.

Add a dedicated `openWorkProduct({ companyId, id })` IPC backed by
`resolveWorkProductTarget` on the DB layer. The resolver joins the
work-product row back to its originating task → workspace (or run →
workspace for taskless runs), composes an absolute path, and rejects
any relative fragment that would escape the workspace root. The
renderer now passes the work product's id — path resolution stays on
the main process where the managed-path policy already lives.

src/main/database.ts

@@ -98,6 +98,7 @@ export class AppDatabase extends AppDatabaseBase {
   updateWorkProduct(id: string, companyId: string, patch: Parameters<ReturnType<typeof import("./database/documents").buildDocumentMethods>["updateWorkProduct"]>[2]) { return this.documentsMod.updateWorkProduct(id, companyId, patch); }
   listWorkProductsForTask(taskId: string, companyId: string) { return this.documentsMod.listWorkProductsForTask(taskId, companyId); }
   findWorkProductByExternalId(companyId: string, provider: string, externalId: string) { return this.documentsMod.findWorkProductByExternalId(companyId, provider, externalId); }
+  resolveWorkProductTarget(workProductId: string, companyId: string) { return this.documentsMod.resolveWorkProductTarget(workProductId, companyId); }
   deleteWorkProduct(id: string, companyId: string) { return this.documentsMod.deleteWorkProduct(id, companyId); }
   linkDocumentToTask(taskId: string, documentId: string, companyId: string, key: string) { return this.documentsMod.linkDocumentToTask(taskId, documentId, companyId, key); }
   unlinkDocumentFromTask(taskId: string, key: string, companyId: string) { this.documentsMod.unlinkDocumentFromTask(taskId, key, companyId); }