Update the workspace MCP docs to feature hosted MCP vs sidecar

[piiq]

Updates the Workspace MCP docs for the hosted backend flow.

• Replaces the sidecar install, health check, CORS, and local 127.0.0.1:8787 setup with Workspace MCP Companion setup.
• Documents the hosted /mcp endpoint, Workspace MCP personal access token creation, bearer header auth, and browser bridge connection.
• Updates the tool reference wording from sidecar to Workspace MCP server and expands the app-builder resource list.
• Refreshes the generated agent text and search metadata so public docs and LLM-facing docs match the source pages.

Related backend PR: https://github.com/OpenBB-finance/openbb-hub/pull/611
Related frontend PR: https://github.com/OpenBB-finance/terminalpro/pull/2052