Reorganize repo: backend/, deploy/, docs/ layout + AGENTS.md

Restructure the monorepo into clear top-level directories:
- backend/: Go module root (cmd, internal, pkg, configs, migrations,
  docs/swagger, scripts, tests, go.mod, Makefile, .air.toml)
- deploy/: Docker (Dockerfile, docker-compose*), quickstart, fluentd
- docs/: project documentation + reports/ (moved from repo root)
- AGENTS.md: new AI coding-agent guide at repo root

Update all references to the new layout:
- Dockerfile: COPY backend/go.mod, COPY backend/ (context = repo root)
- docker-compose files: context ../.., dockerfile deploy/docker/Dockerfile,
  env_file ../../.env, volume mounts ../../backend:/app
- deploy/quickstart/compose.yaml: dockerfile deploy/docker/Dockerfile
- CI: working-directory: backend for go commands, file deploy/docker/Dockerfile,
  coverage path backend/coverage.out, health_check backend/scripts/
- backend/Makefile: docker target uses -f ../deploy/docker/Dockerfile ../
- README: architecture tree, quickstart, config paths updated

Move root stray scripts (rename_models.*, run_m11_tests.sh, verify_build.sh,
gorm_bool_main.go) to backend/scripts/legacy/. All moves via git mv to
preserve history. Build, vet, SQLite tests, and docker compose config verified.

backend/internal/model/channel/microsoft.go

@@ -0,0 +1,64 @@
+package channel
+
+import "github.com/gochat/gochat/internal/model"
+
+// ChannelMicrosoft represents a Microsoft (Azure AD/Teams) channel.
+// Reference: Chatwoot does not have a native Microsoft channel — this is a gochat addition.
+//
+// Enterprise Microsoft integration uses Azure AD OAuth for authentication
+// and Microsoft Graph API for Teams messaging.
+//
+// Features:
+//   - Azure AD OAuth 2.0 authorization flow for enterprise SSO
+//   - Microsoft Teams channel messaging via Graph API
+//   - Outlook email integration potential
+//   - Azure webhook subscriptions for real-time events
+type ChannelMicrosoft struct {
+	model.Base
+
+	// Account foreign key
+	AccountID uint `gorm:"index;not null" json:"account_id"`
+
+	// Inbox foreign key — links to the Inbox that wraps this channel
+	InboxID uint `gorm:"not null;uniqueIndex" json:"inbox_id"`
+
+	// Azure AD tenant ID — identifies the Azure organization
+	TenantID string `gorm:"size:255;not null" json:"tenant_id"`
+
+	// Azure AD client/object ID for the application
+	ClientID string `gorm:"size:255;not null" json:"client_id"`
+
+	// Microsoft Graph API access token
+	AccessToken string `gorm:"size:2048;not null" json:"-"`
+
+	// OAuth 2.0 refresh token for token renewal
+	RefreshToken string `gorm:"size:2048" json:"-"`
+
+	// Microsoft Teams team ID (optional — for Teams channel integration)
+	TeamID string `gorm:"size:255" json:"team_id,omitempty"`
+
+	// Microsoft Teams channel ID (optional — for specific Teams channel)
+	ChannelID string `gorm:"size:255" json:"channel_id,omitempty"`
+
+	// Display name of the connected Microsoft resource
+	DisplayName string `gorm:"size:255" json:"display_name,omitempty"`
+
+	// Webhook subscription ID for Graph API subscriptions
+	SubscriptionID string `gorm:"size:255" json:"subscription_id,omitempty"`
+
+	// Flag indicating reauthorization is required
+	ReauthorizationRequired bool `gorm:"default:false" json:"reauthorization_required,omitempty"`
+}
+
+func (ChannelMicrosoft) TableName() string { return "channel_microsoft" }
+
+func (c ChannelMicrosoft) GetChannelBase() ChannelBase {
+	return ChannelBase{
+		ID:          c.ID,
+		AccountID:   c.AccountID,
+		InboxID:     c.InboxID,
+		ChannelType: "microsoft",
+	}
+}
+
+func (c ChannelMicrosoft) GetChannelType() string { return "microsoft" }