Single panel: outline tree with slots, node search with type filter

The outline and blocks are no longer tabs: one panel shows the
outline tree, the new-block palette and a search over existing
nodes. Outline rows drag to reorder (same snap engine, explicit
gap targets), palette blocks and searched nodes drop onto the
outline gaps as well as the page.

Named slots (x-graph.connections, e.g. a pdp's info-section /
3d-accessories / model) render as groups under their block with
allowed types, live counts and a slot-limited insert picker.
Drops that fit no plain-children rule resolve to the first
accepting slot; existing nodes link via graft tree.link.

Adds Api.searchNodes, schema connections helpers, handle-aware
controller ops (linkExisting, insertIntoSlot, dropExisting) and
mock support for /api/nodes listing and graft links.

🤖 Generated with Codebuff
Co-Authored-By: Codebuff <noreply@codebuff.com>

test/titles.test.tsx

@@ -43,8 +43,8 @@ describe('node titles (x-graph.label)', () => {
     h = await setup()
     await h.settle()
     await h.settle()
-    await h.press('Outline')
-    const items = qa('.cms-outline li button')
+    await h.press('Panel')
+    const items = qa('.cms-orow__main')
     const s1 = items.find((b) => b.textContent!.includes('Welcome'))!
     expect(s1.querySelector('.cms-outline__type')!.textContent).toBe('Welcome')
     expect(s1.querySelector('.cms-outline__text')!.textContent).toBe('section')
@@ -105,7 +105,7 @@ describe('groups in the UI', () => {
   it('the palette is grouped by x-graph.group (collapsible), blueprints last', async () => {
     h = await setup()
     await h.settle()
-    await h.press('Blocks')
+    await h.press('Panel')
     await h.settle()
     await h.settle()
     const secs = qa('.cms-group-sec')
@@ -134,7 +134,7 @@ describe('the block list shows titles and groups straight from /api/types', () =
   it('seeds every schema from the one types request - no per-type schema fetches for the palette', async () => {
     h = await setup()
     await h.settle()
-    await h.press('Blocks')
+    await h.press('Panel')
     await h.settle()
     await h.settle()
     // /api/types carries each type's schema: types that are not on the page are never fetched individually
@@ -147,7 +147,7 @@ describe('the block list shows titles and groups straight from /api/types', () =
   it('palette items show the schema title with the type id underneath (disambiguates look-alikes)', async () => {
     h = await setup()
     await h.settle()
-    await h.press('Blocks')
+    await h.press('Panel')
     await h.settle()
     const heading = q('.cms-block[data-type="heading"]')
     expect(heading.querySelector('span')!.textContent).toBe('Heading')
@@ -162,7 +162,7 @@ describe('the block list shows titles and groups straight from /api/types', () =
     await h.settle()
     expect(h.editor.ctrl.isStaticRoot('page')).toBe(true)
     expect(h.editor.ctrl.isStaticRoot('heading')).toBe(false)
-    await h.press('Blocks')
+    await h.press('Panel')
     await h.settle()
     expect(qa('.cms-block[data-type="page"]')).toHaveLength(0)
     expect(qa('.cms-group-sec summary').map((s) => s.textContent)).not.toContain('Pages')