refactor(mcp): connect Claude Code via direct HTTP, remove stdio bridge

Claude Code now supports MCP servers over HTTP natively (type: "http"
in .mcp.json). The stdio↔HTTP bridge binary was a workaround for the
older stdio-only constraint and is no longer needed — the supervisor
NodePort on koala (30320) is reachable over Tailscale from any client
machine.

Removed:
- cmd/bridge/ (Go source, ~60 lines)
- bin/supervisor-bridge artifact
- Taskfile bridge:build target and the build aggregate's reference
- README "Build the bridge binary" instruction

Updated:
- .mcp.json switched to {type:"http", url:"http://koala:30320/mcp"}
- README architecture diagram and "Connect a project" section

Behavioural prerequisite for this change shipped in 7f7524c
(notifications fix). Verified end-to-end: tier tool call returns
{tier:2, label:"lan-only"} via direct HTTP, no shim.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cmd/bridge/main.go

@@ -1,59 +0,0 @@
-// bridge is a stdio↔HTTP adapter that lets Claude Code connect to the
-// supervisor MCP server via the stdio transport.
-//
-// Claude Code spawns this binary as a subprocess and communicates over
-// stdin/stdout. Each newline-delimited JSON-RPC message from stdin is
-// forwarded to the supervisor HTTP server and the response is written back.
-//
-// Usage:
-//
-//	SUPERVISOR_URL=http://localhost:3200/mcp bridge
-package main
-
-import (
-	"bufio"
-	"bytes"
-	"fmt"
-	"io"
-	"net/http"
-	"os"
-)
-
-func main() {
-	url := os.Getenv("SUPERVISOR_URL")
-	if url == "" {
-		url = "http://localhost:3200/mcp"
-	}
-
-	client := &http.Client{}
-	scanner := bufio.NewScanner(os.Stdin)
-	scanner.Buffer(make([]byte, 1024*1024), 1024*1024)
-
-	for scanner.Scan() {
-		line := scanner.Bytes()
-		if len(bytes.TrimSpace(line)) == 0 {
-			continue
-		}
-
-		req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(line))
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "bridge: build request: %v\n", err)
-			continue
-		}
-		req.Header.Set("Content-Type", "application/json")
-
-		resp, err := client.Do(req)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "bridge: request failed: %v\n", err)
-			continue
-		}
-		_, _ = io.Copy(os.Stdout, resp.Body)
-		_ = resp.Body.Close()
-		_, _ = os.Stdout.Write([]byte("\n"))
-	}
-
-	if err := scanner.Err(); err != nil {
-		fmt.Fprintf(os.Stderr, "bridge: scanner: %v\n", err)
-		os.Exit(1)
-	}
-}