chore(web): remove the Ralph wizard and its plan-generation UI

The wizard's only entry point was the "Start Ralph Loop" button on the
start screen, removed in 1.50.0, so none of this could be opened or
triggered from the app any more:

- ralph-wizard.js (the wizard, plan generation flow and the floating plan
  subagent windows) and the #ralphWizardModal markup;
- the "Plan Wizard Agents" section of the monitor panel with its cancel
  button, and the five plan:* SSE handlers that only fed these surfaces;
- the wizard branches in the subagent window code: connection lines to
  the wizard and to plan agents, window placement beside the wizard, and
  the wizard cleanup on reconnect. The ordinary path (agent window to its
  parent tab) is unchanged, only un-nested;
- the wizard's state on the app object and its z-index constant;
- its styles: 67 classes, three keyframes and a second identical
  @keyframes spin.

What stays: the Ralph panel, the Ralph tab in session options, the plan
routes (/api/generate-plan, /api/generate-plan-detailed,
/api/cancel-plan-generation, the ralph-wizard file routes) and the
plan:* SSE events, which are part of the public API. A client that
starts plan generation over the API still gets its events; the page no
longer draws anything for them.

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>

test/tab-rail-search.browser.test.ts

@@ -277,7 +277,6 @@ describe('vertical rail session search in Chromium', () => {
         ['ag1', { element: document.getElementById('subWin'), minimized: false, hidden: false }],
       ]);
       app.subagentParentMap = new Map([['ag1', 'alpha']]);
-      app.planSubagents = new Map();
     });
     try {
       const anchor = await rowAnchor();

test/tab-rail-search.test.ts

@@ -801,7 +801,6 @@ describe('floating windows whose parent row the search hid', () => {
       ['ag1', { element: document.getElementById('subWin'), minimized: false, hidden: false }],
     ]);
     app.subagentParentMap = new Map([['ag1', 'review']]);
-    app.planSubagents = new Map();
     app.ultracodeWindows = new Map([
       ['run1', { element: document.getElementById('runWin'), parentSessionId: 'review' }],
     ]);