feat(mcp): stdio MCP server exposing the full API as tools

Add containr-mcp so MCP-compatible agents (Claude, Cursor, Devin)
operate the platform directly — ROADMAP2 phase A3. Reuses the CLI's
thin client and PAT auth; zero duplicated resource logic.

- ~60 containr_* tools across projects, services, deployments, logs,
  exec, variables, databases, cron, templates, nodes, scaling, ha,
  security, gateway, admin, notifications, tokens
- declarative tool specs → {param} path substitution, GET extras become
  query params, remaining args form the request body
- destructive tools require confirm:true and return isError without it
- results are pretty JSON; API error envelopes surface as isError
- configured via CONTAINR_API_URL + CONTAINR_TOKEN env; official
  modelcontextprotocol/go-sdk over StdioTransport

Verified over stdio: initialize + tools/list, auth_status returns the
token owner's identity, projects list, destructive refusal, token
creation through MCP.

Authored By: TDvorak <[email protected]>

app/backend/go.mod

@@ -8,11 +8,12 @@ require (
 	github.com/gin-gonic/gin v1.9.1
 	github.com/go-playground/validator/v10 v10.30.1
 	github.com/go-redis/redis/v8 v8.11.5
-	github.com/golang-jwt/jwt/v5 v5.2.2
+	github.com/golang-jwt/jwt/v5 v5.3.1
 	github.com/google/uuid v1.6.0
 	github.com/gorilla/websocket v1.5.3
 	github.com/lib/pq v1.10.9
 	github.com/miekg/dns v1.1.72
+	github.com/modelcontextprotocol/go-sdk v1.7.0
 	github.com/pressly/goose/v3 v3.24.1
 	github.com/robfig/cron/v3 v3.0.1
 	github.com/rs/cors v1.10.1
@@ -21,6 +22,7 @@ require (
 	github.com/sqlc-dev/pqtype v0.3.0
 	github.com/stretchr/testify v1.11.1
 	golang.org/x/crypto v0.57.0
+	golang.org/x/term v0.46.0
 )
 
 require (
@@ -45,6 +47,7 @@ require (
 	github.com/go-playground/universal-translator v0.18.1 // indirect
 	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
 	github.com/goccy/go-json v0.10.2 // indirect
+	github.com/google/jsonschema-go v0.4.3 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/klauspost/cpuid/v2 v2.2.4 // indirect
@@ -63,6 +66,8 @@ require (
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/sagikazarmark/locafero v0.11.0 // indirect
+	github.com/segmentio/asm v1.2.0 // indirect
+	github.com/segmentio/encoding v0.5.4 // indirect
 	github.com/sethvargo/go-retry v0.3.0 // indirect
 	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
 	github.com/spf13/afero v1.15.0 // indirect
@@ -71,6 +76,7 @@ require (
 	github.com/subosito/gotenv v1.6.0 // indirect
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
 	github.com/ugorji/go/codec v1.2.11 // indirect
+	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.60.0 // indirect
 	go.opentelemetry.io/otel v1.41.0 // indirect
@@ -84,11 +90,11 @@ require (
 	golang.org/x/arch v0.3.0 // indirect
 	golang.org/x/mod v0.41.0 // indirect
 	golang.org/x/net v0.59.0 // indirect
+	golang.org/x/oauth2 v0.35.0 // indirect
 	golang.org/x/sync v0.23.0 // indirect
 	golang.org/x/sys v0.48.0 // indirect
-	golang.org/x/term v0.46.0 // indirect
 	golang.org/x/text v0.42.0 // indirect
-	golang.org/x/time v0.11.0 // indirect
+	golang.org/x/time v0.15.0 // indirect
 	golang.org/x/tools v0.49.0 // indirect
 	google.golang.org/protobuf v1.36.11 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect