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/reporting_event.go

@@ -0,0 +1,80 @@
+package model
+
+import (
+	"time"
+)
+
+// ReportingEvent represents a raw event for real-time analytics.
+// Reference: Chatwoot ReportingEvent model — captures first_response, resolution_time,
+// reply_time, avg_first_response_time, avg_resolution_time, resolutions_count,
+// bot_resolutions_count, bot_handoffs_count.
+type ReportingEvent struct {
+	Base
+	AccountID             uint      `gorm:"index;not null" json:"account_id"`
+	Name                  string    `gorm:"size:100;index;not null" json:"name"` // metric name: first_response, resolution_time, etc.
+	Value                 float64   `json:"value"`
+	ValueInBusinessHours  float64   `json:"value_in_business_hours"`
+	ConversationID        *uint     `gorm:"index" json:"conversation_id,omitempty"`
+	InboxID               *uint     `gorm:"index" json:"inbox_id,omitempty"`
+	UserID                *uint     `gorm:"index" json:"user_id,omitempty"`
+	EventStartTime        time.Time `gorm:"index" json:"event_start_time"`
+	EventEndTime          time.Time `gorm:"index" json:"event_end_time"`
+
+	Account      *Account      `gorm:"foreignKey:AccountID" json:"account,omitempty"`
+	Inbox        *Inbox        `gorm:"foreignKey:InboxID" json:"inbox,omitempty"`
+	Conversation *Conversation `gorm:"foreignKey:ConversationID" json:"conversation,omitempty"`
+	User         *User         `gorm:"foreignKey:UserID" json:"user,omitempty"`
+}
+
+func (ReportingEvent) TableName() string { return "reporting_events" }
+
+// DimensionType represents the dimension category for rollup aggregation.
+type DimensionType string
+
+const (
+	DimensionAccount      DimensionType = "account"
+	DimensionAgent        DimensionType = "agent"
+	DimensionInbox        DimensionType = "inbox"
+	DimensionTeam         DimensionType = "team"
+	DimensionLabel        DimensionType = "label"
+	DimensionConversation DimensionType = "conversation"
+)
+
+// MetricName constants are used as string identifiers for reporting event queries.
+const (
+	MetricNameFirstResponse       = "first_response"
+	MetricNameReplyTime           = "reply_time"
+	MetricNameResolutionTime      = "resolution_time"
+	MetricNameBotResolutionsCount = "bot_resolutions_count"
+	MetricNameBotHandoffsCount    = "bot_handoffs_count"
+	MetricBotResolutions          = "bot_resolutions"
+	MetricBotHandoffs             = "bot_handoffs"
+)
+
+// RollupMetric represents the metric names used in rollup records.
+type RollupMetric string
+
+const (
+	MetricResolutionsCount    RollupMetric = "resolutions_count"
+	MetricFirstResponse       RollupMetric = "first_response"
+	MetricResolutionTime      RollupMetric = "resolution_time"
+	MetricReplyTime           RollupMetric = "reply_time"
+	MetricBotResolutionsCount RollupMetric = "bot_resolutions_count"
+	MetricBotHandoffsCount    RollupMetric = "bot_handoffs_count"
+)
+
+// ReportingEventsRollup stores pre-aggregated reporting data per day/dimension/metric.
+// Reference: Chatwoot ReportingEventsRollup — unique index on (account_id, date, dimension_type, dimension_id, metric).
+type ReportingEventsRollup struct {
+	Base
+	AccountID           uint          `gorm:"uniqueIndex:idx_rollup_unique;not null" json:"account_id"`
+	Date                time.Time     `gorm:"uniqueIndex:idx_rollup_unique;type:date;not null" json:"date"`
+	DimensionType       DimensionType `gorm:"uniqueIndex:idx_rollup_unique;size:20;not null" json:"dimension_type"`
+	DimensionID         uint          `gorm:"uniqueIndex:idx_rollup_unique;not null" json:"dimension_id"`
+	Metric              RollupMetric  `gorm:"uniqueIndex:idx_rollup_unique;size:50;not null" json:"metric"`
+	Count               int64         `json:"count"`
+	SumValue            float64       `json:"sum_value"`
+	SumValueBusinessHours float64     `json:"sum_value_business_hours"`
+}
+
+func (ReportingEventsRollup) TableName() string { return "reporting_events_rollups" }