feat(mcp-client): auto-reconnect with bounded backoff after transport close

A per-instance connection supervisor restarts the original server config
with exponential backoff when the transport closes, re-runs tool discovery
on success, and atomically replaces the previous generation. Default policy
retries for ~2.5 minutes (10 attempts, 500ms→30s doubling) before giving up
and unregistering the server's tools.

New config block reconnect { enabled, initialDelayMs, maxDelayMs, maxAttempts }
on both transports; misconfiguration fails plugin load. A connection that
survives past the stability window (maxDelayMs) resets the attempt budget,
so occasional crashes recover indefinitely while a crash loop still exhausts
the cap.

Integrates with the upstream failOnStartupError: the initial sync uses
registrationFailure:'throw' when that flag is set so a squatted namespace
still rejects activation.

Fixes #1746

docs/config-catalog.md

@@ -1069,6 +1069,8 @@ export interface StdioConfig {
   toolCallTimeoutMs: number
   /** Fail plugin activation when the initial connection or tool synchronization fails. */
   failOnStartupError: boolean
+  /** Automatic reconnect policy after a lost connection; omission uses the defaults. */
+  reconnect?: ReconnectConfig
 }
 
 /** Config for connecting to an MCP server over Streamable HTTP (SSE). */
@@ -1089,10 +1091,24 @@ export interface StreamableHttpConfig {
   toolCallTimeoutMs: number
   /** Fail plugin activation when the initial connection or tool synchronization fails. */
   failOnStartupError: boolean
+  /** Automatic reconnect policy after a lost connection; omission uses the defaults. */
+  reconnect?: ReconnectConfig
+}
+
+/** Automatic reconnect policy for one MCP server connection. */
+export interface ReconnectConfig {
+  /** Reconnect automatically after a lost connection (default true). */
+  enabled?: boolean
+  /** First reconnect delay in milliseconds; doubles per consecutive failed attempt (default 500). */
+  initialDelayMs?: number
+  /** Backoff ceiling in milliseconds; also the uptime after which the attempt budget resets (default 30000). */
+  maxDelayMs?: number
+  /** Consecutive failed attempts per outage before giving up for good (default 10). */
+  maxAttempts?: number
 }
 ```
 
-Source: [`packages/mcp/mcp-client/src/index.ts:100`](../packages/mcp/mcp-client/src/index.ts)
+Source: [`packages/mcp/mcp-client/src/index.ts:104`](../packages/mcp/mcp-client/src/index.ts)
 
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