feat: Universal auto-instrumentation for all languages

## New Features

### Universal Instrumentation Container
- Created deploy/instrumentation/ with Dockerfile that downloads OTel agents for:
  - .NET (glibc and musl/Alpine versions)
  - Node.js (with auto-instrumentation package)
  - Python (bootstrap script + requirements)
  - Java (javaagent JAR)
  - Go (example code for compile-time instrumentation)
  - PHP (composer package + init script)

### Universal instrument.sh Script
- Auto-detects application language from running processes
- Generates docker-compose snippets for each language
- Supports: dotnet, nodejs, python, java, go, php
- Usage: ./instrument.sh <container> [language] [otlp_endpoint]

### Improved docker-compose.yml
- Added instrumentation init container with shared volume
- Added AGENT_KEY environment variable for proper auth
- Added ophion-agent service for host metrics collection
- Named containers for easier management
- Added ophion-network for service discovery

### Documentation
- Created docs/QUICK_START.md with:
  - Single-command installation
  - Instrumentation guide for all languages
  - Troubleshooting section
  - Authentication guide

### Auth Fixes
- Server now properly validates AGENT_KEY for agent authentication
- OTel Collector configured with AGENT_KEY for forwarding to server
- Fixed 401 errors when agents connect

## Files Changed
- docker-compose.yml: Complete stack with all services
- deploy/instrumentation/*: Universal OTel agent container
- deploy/docker/otel-collector-config.yaml: Fixed auth headers
- instrument.sh: Universal instrumentation script
- docs/QUICK_START.md: Complete quick start guide
- README.md: Updated with new features
- .env.example: Added AGENT_KEY

## Testing
- Go code compiles successfully
- Docker images build correctly
- All changes are backwards compatible

deploy/docker/otel-collector-config.yaml

@@ -1,6 +1,6 @@
 # ═══════════════════════════════════════════════════════════
 # 🐍 OPHION - OpenTelemetry Collector Configuration
-# Receives traces/metrics/logs from instrumented applications
+# Central collector for all instrumented applications
 # ═══════════════════════════════════════════════════════════
 
 receivers:
@@ -14,8 +14,10 @@ receivers:
         cors:
           allowed_origins:
             - "*"
+          allowed_headers:
+            - "*"
 
-  # Prometheus receiver for metrics scraping (optional)
+  # Prometheus receiver for scraping metrics
   prometheus:
     config:
       scrape_configs:
@@ -43,22 +45,24 @@ processors:
       - key: collector.name
         value: ophion-collector
         action: upsert
-      - key: deployment.environment
-        from_attribute: OTEL_RESOURCE_ATTRIBUTES
-        action: upsert
 
-  # Attributes processor for enrichment
-  attributes:
-    actions:
-      - key: ophion.collected
-        value: true
-        action: upsert
+  # Transform processor for data enrichment
+  transform:
+    trace_statements:
+      - context: span
+        statements:
+          - set(attributes["ophion.collected"], true)
+    metric_statements:
+      - context: datapoint
+        statements:
+          - set(attributes["ophion.collected"], true)
 
 exporters:
-  # Export to Ophion server via OTLP
-  otlphttp/ophion:
+  # Export traces to Ophion server via HTTP
+  otlphttp/traces:
     endpoint: http://server:8080
     headers:
+      Authorization: "Bearer ${env:AGENT_KEY}"
       X-Ophion-Source: otel-collector
     compression: gzip
     retry_on_failure:
@@ -67,13 +71,29 @@ exporters:
       max_interval: 30s
       max_elapsed_time: 300s
 
-  # Debug exporter for troubleshooting (disable in production)
+  # Export metrics to Ophion server
+  otlphttp/metrics:
+    endpoint: http://server:8080
+    headers:
+      Authorization: "Bearer ${env:AGENT_KEY}"
+      X-Ophion-Source: otel-collector
+    compression: gzip
+
+  # Export logs to Ophion server
+  otlphttp/logs:
+    endpoint: http://server:8080
+    headers:
+      Authorization: "Bearer ${env:AGENT_KEY}"
+      X-Ophion-Source: otel-collector
+    compression: gzip
+
+  # Debug exporter for troubleshooting
   debug:
     verbosity: basic
     sampling_initial: 5
     sampling_thereafter: 200
 
-  # Prometheus exporter for collector metrics
+  # Prometheus exporter for collector's own metrics
   prometheus:
     endpoint: 0.0.0.0:8889
     namespace: ophion_collector
@@ -99,20 +119,20 @@ service:
     # Traces pipeline
     traces:
       receivers: [otlp]
-      processors: [memory_limiter, batch, resource, attributes]
-      exporters: [otlphttp/ophion, debug]
+      processors: [memory_limiter, batch, resource, transform]
+      exporters: [otlphttp/traces, debug]
 
-    # Metrics pipeline  
+    # Metrics pipeline
     metrics:
       receivers: [otlp, prometheus]
       processors: [memory_limiter, batch, resource]
-      exporters: [otlphttp/ophion, debug]
+      exporters: [otlphttp/metrics, debug]
 
     # Logs pipeline
     logs:
       receivers: [otlp]
       processors: [memory_limiter, batch, resource]
-      exporters: [otlphttp/ophion, debug]
+      exporters: [otlphttp/logs, debug]
 
   telemetry:
     logs: