feat(mcp): per-requester OAuth for MCP servers (#122166)

Per-requester OAuth for HTTP MCP servers: in shared channels each trusted sender connects their own account. New config: mcp.servers.<name>.oauth.identity ("shared" default, byte-identical behavior) and gateway.publicOrigin (HTTPS except loopback) for the new GET /oauth/mcp/callback served on the Gateway HTTP server. Requester tokens are isolated per (channel, account, sender) in mcp_oauth_stores rows (no schema bump); callbacks correlate through a durable state-keyed one-time index with a 10-minute TTL; per-requester servers are fail-closed out of static/scheduled runtimes; unauthenticated senders get a sign-in link with a portable URL button; MCP config mutations clear requester credentials at the canonical owner. mcp status --json keeps the legacy authStatus fields additively. Proven by a two-user self-hosted-Executor E2E through the real gateway callback. Part of #122034.

Co-authored-by: Ayaan Zaidi <hi@obviy.us>

docs/.generated/plugin-sdk-api-baseline/provider-auth.json

@@ -1 +1 @@
-{"contentHash":"d5d21f2a0883eac72d6642d93306c36e2de0f3851286eb3edbe3a2d9d6122dcc","entrypoint":"provider-auth","importSpecifier":"openclaw/plugin-sdk/provider-auth"}
+{"contentHash":"1b51ace8b1e469c12e17dfe749484bbfa624781917e346a431bfe76eb1c286c3","entrypoint":"provider-auth","importSpecifier":"openclaw/plugin-sdk/provider-auth"}