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>

Taskfile.yml

@@ -57,7 +57,6 @@ tasks:
     desc: Build all binaries
     cmds:
       - task: supervisor:build
-      - task: bridge:build
       - task: ingestion:build
 
   supervisor:build:
@@ -65,11 +64,6 @@ tasks:
     cmds:
       - go build -trimpath -ldflags="-s -w -X main.version={{.VERSION}}" -o bin/supervisor ./cmd/supervisor
 
-  bridge:build:
-    desc: Build stdio↔HTTP bridge for Claude Code MCP integration
-    cmds:
-      - go build -trimpath -ldflags="-s -w" -o bin/supervisor-bridge ./cmd/bridge
-
   ingestion:build:
     desc: Build ingestion server binary
     dir: ingestion