fix(dockview-vue): accept components via prop (resolves #1301)

[mathuo]

Summary

• Adds components and tabComponents map props to <DockviewVue>, and lets every singular slot prop (defaultTabComponent, watermarkComponent, *HeaderActionsComponent, tabGroupChipComponent, groupDragGhostComponent) accept a component object directly — matching the React (packages/dockview/src/dockview/dockview.tsx) and Angular (packages/dockview-angular/src/lib/dockview/types.ts) APIs.
• Resolves The component must be globally registered in main.ts to find the component to render in the panel #1301: <script setup> users were forced to register every panel component globally via app.component(...) in main.ts, because findComponent only walked the instance-component tree and the app registry — neither of which <script setup> imports populate. Now <DockviewVue :components="{ Foo: MyFoo }" /> works without any global registration.
• Fully additive — the existing Options-API local-registration and global app.component(...) paths still resolve as before.
• defaultTabComponent as a component object uses a DEFAULT_VUE_TAB sentinel routed through createTabComponent, mirroring React's DEFAULT_REACT_TAB.
• Also fixes the mistyped components: Record<string, string> on splitview/gridview/paneview types (now Record<string, VueComponent> and actually wired through useViewComponent).

Test plan

• All 110 unit tests pass (78 baseline + 32 new) — yarn workspace dockview-vue run test --run
• vue-tsc type check clean — yarn workspace dockview-vue run build:types
• New tests cover: findComponent map-priority/fallthrough/error paths, resolveComponent all branches, <DockviewVue> with bare components prop (no global registration), tabComponents map, every singular slot prop accepting a component object, sentinel routing for defaultTabComponent, runtime map swap, equivalent coverage for splitview/gridview/paneview
• Manual smoke in a <script setup> app to confirm the reporter's scenario (recommended before merge)
• Docs preview build clean (packages/docs/docs/core/panels/register.mdx, packages/docs/docs/overview/quickstart.mdx rewritten to show the new <script setup> + :components pattern)

Fixes #1301

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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