feat(mcp): add 34 official vendor-hosted remote MCP servers to the catalog

Competitor-parity expansion (Perplexity Computer, Manus, Claude, ChatGPT
connector catalogs) limited to endpoints a generic MCP client can actually
use. Every entry was live-probed: initialize handshake for no-auth servers,
RFC 9728 protected-resource metadata -> AS metadata with a
registration_endpoint for OAuth servers (true DCR only).

No-auth (7): deepwiki, context7, microsoft-learn, exa, aws-knowledge,
wolfram, telnyx*
API key (3): github (PAT bearer - GitHub reserves browser OAuth for
pre-registered IDEs), perplexity, telnyx
OAuth 2.1 + DCR (24): canva, zapier, monday, clickup, todoist, dropbox,
wix, miro, calendly, ramp, plaid, fireflies, neon, prisma-postgres,
postman, globalping, buildkite, semgrep, attio, close, apify, cloudinary,
parallel-search, twelve-data, indeed

Deliberately excluded after probing OAUTH_NO_DCR (vendor requires a
pre-registered app; generic clients cannot connect): Box, Slack, HubSpot,
Zoom, PagerDuty, Brex, Docusign, Stack Overflow, Google Workspace.

optional-mcps/dropbox/manifest.yaml

@@ -0,0 +1,32 @@
+# Nous-approved MCP catalog entry.
+# Presence in this directory = approval. Merged via PR review.
+manifest_version: 1
+
+name: dropbox
+description: Search, read, and manage files in Dropbox.
+source: https://help.dropbox.com/integrations/connect-dropbox-mcp-server
+
+# Official vendor-hosted remote MCP (URL-only — Hermes never spawns a local
+# process for this entry). Native OAuth 2.1 + Dynamic Client Registration
+# (verified live: RFC 9728 protected-resource metadata -> AS metadata with
+# registration_endpoint); Hermes's MCP client + mcp_oauth_manager handle
+# discovery, PKCE, token exchange, and refresh.
+
+transport:
+  type: http
+  url: https://mcp.dropbox.com/mcp
+
+auth:
+  type: oauth
+
+# Composer-suggestion triggers (desktop brand pills).
+suggest:
+  keywords:
+    - dropbox
+  hosts:
+    - dropbox.com
+
+post_install: |
+  On first connection Hermes opens a browser to authorize with
+  Dropbox (or run `hermes mcp login dropbox`). Approve access,
+  then restart the session so tools load.