Remove Phoenix & Notebooks - Phase 2: Remove in-app notebook authoring & rendering (#2515)

Delete the nteract rendering engine, notebook tabs, panes, the read-only viewer, Schema Analyzer (pulled forward from Phase 3), and all UI entry points that open notebooks. Decouple surviving files (Explorer, NotebookManager, useNotebook, ResourceTreeAdapter) with minimal edits, keeping GitHub/Juno/Phoenix wiring for later phases.

Removed 22 zero-importer notebook-only npm deps; re-added phantom transitively-hoisted deps still used by surviving code: xterm, xterm-addon-fit (CloudShell), d3-collection (Graph), @nteract/myths (@nteract/core).

Verified: compile, compile:strict, lint (0 errors), format:check, test (1945 passing), build:ci all green.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

package.json

@@ -13,35 +13,14 @@
     "@babel/plugin-proposal-decorators": "7.12.12",
     "@fluentui/react": "8.119.0",
     "@fluentui/react-components": "9.54.2",
-    "@jupyterlab/services": "6.0.2",
-    "@jupyterlab/terminal": "3.6.8",
     "@microsoft/applicationinsights-web": "2.6.1",
     "@nteract/commutable": "7.5.1",
-    "@nteract/connected-components": "6.8.2",
     "@nteract/core": "15.1.9",
-    "@nteract/data-explorer": "8.2.12",
-    "@nteract/directory-listing": "2.0.6",
-    "@nteract/dropdown-menu": "1.0.1",
-    "@nteract/editor": "10.1.12",
     "@nteract/fixtures": "2.3.0",
-    "@nteract/iron-icons": "1.0.0",
-    "@nteract/jupyter-widgets": "2.0.0",
-    "@nteract/logos": "1.0.0",
     "@nteract/markdown": "4.6.0",
-    "@nteract/monaco-editor": "3.2.2",
-    "@nteract/octicons": "2.0.0",
-    "@nteract/outputs": "3.0.9",
-    "@nteract/presentational-components": "3.4.12",
-    "@nteract/stateful-components": "1.7.0",
-    "@nteract/styles": "2.0.2",
-    "@nteract/transform-geojson": "5.1.8",
-    "@nteract/transform-model-debug": "5.0.1",
-    "@nteract/transform-plotly": "6.1.6",
-    "@nteract/transform-vdom": "4.0.11",
-    "@nteract/transform-vega": "7.0.6",
+    "@nteract/myths": "0.1.9",
     "@octokit/request": "8.4.1",
     "@octokit/rest": "17.9.2",
-    "@phosphor/widgets": "1.9.3",
     "@testing-library/jest-dom": "6.4.6",
     "@types/lodash": "4.14.171",
     "@types/mkdirp": "1.0.1",
@@ -59,6 +38,7 @@
     "crossroads": "0.12.2",
     "css-element-queries": "1.1.1",
     "d3": "7.9.0",
+    "d3-collection": "1.0.7",
     "datatables.net-colreorder-dt": "1.7.0",
     "datatables.net-dt": "1.13.8",
     "date-fns": "1.29.0",
@@ -118,6 +98,8 @@
     "uuid": "9.0.0",
     "web-vitals": "4.2.4",
     "ws": "8.20.1",
+    "xterm": "4.19.0",
+    "xterm-addon-fit": "0.5.0",
     "zustand": "3.5.0"
   },
   "overrides": {