feat: add amcs-cli — MCP tool CLI and stdio bridge

- cmd/amcs-cli: new CLI tool for human/AI MCP tool access
- amcs-cli tools: list all tools from remote MCP server
- amcs-cli call <tool> --arg k=v: invoke a tool, print JSON/YAML result
- amcs-cli stdio: stdio→HTTP MCP bridge for AI clients
- Config: ~/.config/amcs/config.yaml, AMCS_URL/AMCS_TOKEN env vars, --server/--token flags
- Token never logged in errors
- Makefile: add build-cli target

Closes #18

go.mod

@@ -8,11 +8,13 @@ require (
 	github.com/jackc/pgx/v5 v5.9.1
 	github.com/modelcontextprotocol/go-sdk v1.4.1
 	github.com/pgvector/pgvector-go v0.3.0
+	github.com/spf13/cobra v1.10.2
 	golang.org/x/sync v0.17.0
 	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
@@ -20,6 +22,7 @@ require (
 	github.com/rogpeppe/go-internal v1.14.1 // indirect
 	github.com/segmentio/asm v1.1.3 // indirect
 	github.com/segmentio/encoding v0.5.4 // indirect
+	github.com/spf13/pflag v1.0.9 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
 	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
 	golang.org/x/oauth2 v0.34.0 // indirect