feat(mcp): simplify MCP server form to URL-first, collapse advanced settings

[esafwan]

Why

The MCP server form exposed ~15 inputs up front — every OAuth value that URL-first discovery (RFC 9728/8414 + DCR + PKCE, from the MCPUrlFirst work) now fills automatically was still a visible manual field. Standard AI tool connector dialog asks only for Name + URL (with Client ID/Secret tucked into Advanced). This PR brings HUF's form to the same surface while keeping the extra capabilities (non-OAuth auth modes, custom headers) that other tools doesn't offer.

What changed

Connection tab (ConnectionTab.tsx)

• Default view is now just MCP Server URL + Connect/Save & Connect + status — nothing else.
• Auth mode, credential field, transport type, and custom headers move into an "Advanced Settings" card, collapsed by default.
• The 7 manual OAuth fields (Client ID/Secret, auth/token endpoints, scope, extra authorize params, redirect URI) move into a nested "Manual OAuth Fallback" collapsible ("only for servers without automatic discovery or client registration"). The backend already treats them as optional overrides (mcp_connection_resolver.py only fills them when empty).
• Credential field is labeled per auth mode (API Key / Token / Header Value); header name stays auto-derived and is only editable for custom_header.

Details tab (DetailsTab.tsx)

• Default view: Server Name, Description, Enabled. Tool Namespace and Timeout move behind a collapsed "Advanced" row.

Removed field: oauth_token_response_path

• Unused compat shim (token extraction always fell back to the standard access_token key in practice). Removed from the DocType, mcp_oauth.py::_save_tokens, and all frontend references.

DocType

• auth_type default changed none → oauth, matching the React form, so URL-first OAuth is the out-of-box path in Desk too.
• Note: Frappe migrate does not drop columns, so the oauth_token_response_path DB column remains as an inert orphan; it can be dropped manually later if desired.

Screenshots (bench 16_ro, huf-ro.localhost)

Default view — URL + Connect only:

Advanced Settings expanded (auth mode / transport / custom headers):

Manual OAuth Fallback (nested, collapsed by default):

Details tab:

The screenshots live in docs/screenshots/mcp-form-simplify/ in a separate commit that can be dropped before merge if you don't want them in the repo history.

Test plan

• yarn build (tsc + vite) green on host worktree and in bench container
• Deployed to bench 16_ro (isolated validation bench), bench migrate clean
• Browser walkthrough on huf-ro.localhost — all four states above verified live (screenshots)
• Smoke: MCP Server insert via console — auth_type defaults to oauth, token_response_path gone from meta, delete clean
• Connect flow against a real OAuth MCP server (e.g. mcp.higgsfield.ai) — unchanged code path, but worth one manual click-through before merge

[esafwan]

Update: Agent MCP section — one button, create path in the flow

Follow-up commit on this branch addressing the Create MCP / Connect MCP button pair in the Agent form's MCP card — two near-synonyms for the same end result (the sign-in/sign-up dilemma). Design validated via a claude opus UX consult.

What changed (ToolsTab.tsx, SelectMCPServersModal.tsx, AgentFormPage.tsx)

• One button everywhere: Connect MCP Server (secondary in the card header, primary in the empty state). The separate "Create MCP" button is gone.
• The picker modal is now titled "Connect MCP servers" — "Select from your registered servers, or register a new one." — and carries a quiet footer link "Don't see it? Register a new MCP server →" that routes into the existing /mcp/new?agent=<id> create flow.
• Empty-registry edge case: if no MCP servers exist at all, the modal promotes the create path to primary — "No MCP servers registered yet" + "Register your first MCP server →" — so first-run users get a clear CTA instead of a dead-end list.
• Empty-state copy in the card: "No MCP servers connected yet / Connect a shared server, or register a new one to get started."

Screenshots (bench 16_ro, live):

Agent MCP card — single button in header and empty state:

Picker modal, populated registry — list + footer create link:

Picker modal, empty registry — create path promoted to primary:

Verified: yarn build (tsc + vite) green, deployed on bench 16_ro, all three states captured live via headless Chrome. Dummy data used for the populated shot was removed afterward.

[esafwan]

Superseded by consolidated MCP PR #466, now included in integration PR #468.