feat(epic1): complete OpenTelemetry integration and add verification documentation

Story 1.6: OpenTelemetry Distributed Tracing
- Implemented tracer initialization with stdout (dev) and OTLP (prod) exporters
- Added HTTP request instrumentation via Gin middleware
- Integrated trace ID correlation in structured logs
- Added tracing configuration to config files
- Registered tracer provider in DI container

Documentation and Setup:
- Created Docker Compose setup for PostgreSQL database
- Added comprehensive Epic 1 summary with verification instructions
- Added Epic 0 summary with verification instructions
- Linked summaries in documentation index and epic READMEs
- Included detailed database testing instructions
- Added Docker Compose commands and troubleshooting guide

All Epic 1 stories (1.1-1.6) are now complete. Story 1.7 depends on Epic 2.

go.mod

@@ -4,11 +4,17 @@ go 1.24
 
 require (
 	entgo.io/ent v0.14.5
-	github.com/gin-gonic/gin v1.9.1
+	github.com/gin-gonic/gin v1.10.1
 	github.com/google/uuid v1.6.0
 	github.com/lib/pq v1.10.9
 	github.com/prometheus/client_golang v1.23.2
 	github.com/spf13/viper v1.18.0
+	go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin v0.63.0
+	go.opentelemetry.io/otel v1.38.0
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.38.0
+	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.38.0
+	go.opentelemetry.io/otel/sdk v1.38.0
+	go.opentelemetry.io/otel/trace v1.38.0
 	go.uber.org/fx v1.24.0
 	go.uber.org/zap v1.26.0
 )
@@ -19,31 +25,36 @@ require (
 	github.com/apparentlymart/go-textseg/v15 v15.0.0 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/bmatcuk/doublestar v1.3.4 // indirect
-	github.com/bytedance/sonic v1.9.1 // indirect
+	github.com/bytedance/sonic v1.14.0 // indirect
+	github.com/bytedance/sonic/loader v0.3.0 // indirect
+	github.com/cenkalti/backoff/v5 v5.0.3 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
-	github.com/chenzhuoyu/base64x v0.0.0-20221115062448-fe3a3abad311 // indirect
+	github.com/cloudwego/base64x v0.1.6 // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
-	github.com/gabriel-vasile/mimetype v1.4.2 // indirect
-	github.com/gin-contrib/sse v0.1.0 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.10 // indirect
+	github.com/gin-contrib/sse v1.1.0 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-openapi/inflect v0.19.0 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
-	github.com/go-playground/validator/v10 v10.14.0 // indirect
-	github.com/goccy/go-json v0.10.2 // indirect
+	github.com/go-playground/validator/v10 v10.27.0 // indirect
+	github.com/goccy/go-json v0.10.5 // indirect
 	github.com/google/go-cmp v0.7.0 // indirect
+	github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.2 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/hashicorp/hcl/v2 v2.18.1 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
-	github.com/klauspost/cpuid/v2 v2.2.4 // indirect
-	github.com/leodido/go-urn v1.2.4 // indirect
+	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
+	github.com/leodido/go-urn v1.4.0 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
-	github.com/mattn/go-isatty v0.0.19 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mitchellh/go-wordwrap v1.0.1 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
-	github.com/pelletier/go-toml/v2 v2.1.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect
 	github.com/prometheus/common v0.66.1 // indirect
 	github.com/prometheus/procfs v0.16.1 // indirect
@@ -55,19 +66,26 @@ require (
 	github.com/spf13/pflag v1.0.5 // indirect
 	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/ugorji/go/codec v1.3.0 // indirect
 	github.com/zclconf/go-cty v1.14.4 // indirect
 	github.com/zclconf/go-cty-yaml v1.1.0 // indirect
+	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.38.0 // indirect
+	go.opentelemetry.io/otel/metric v1.38.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.7.1 // indirect
 	go.uber.org/dig v1.19.0 // indirect
 	go.uber.org/multierr v1.10.0 // indirect
 	go.yaml.in/yaml/v2 v2.4.2 // indirect
-	golang.org/x/arch v0.3.0 // indirect
+	golang.org/x/arch v0.20.0 // indirect
 	golang.org/x/crypto v0.41.0 // indirect
 	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
 	golang.org/x/mod v0.26.0 // indirect
 	golang.org/x/net v0.43.0 // indirect
 	golang.org/x/sys v0.35.0 // indirect
 	golang.org/x/text v0.28.0 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20250825161204-c5933d9347a5 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20250825161204-c5933d9347a5 // indirect
+	google.golang.org/grpc v1.75.0 // indirect
 	google.golang.org/protobuf v1.36.8 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect