chore: standardize configuration, logging, and error handling across blockchain node and coordinator API

- Add infrastructure.md and workflow files to .gitignore to prevent sensitive info leaks
- Change blockchain node mempool backend default from memory to database for persistence
- Refactor blockchain node logger with StructuredLogFormatter and AuditLogger (consistent with coordinator)
- Add structured logging fields: service, module, function, line number
- Unify coordinator config with Database

docs/2_clients/3_job-lifecycle.md

@@ -0,0 +1,292 @@
+# Job Status Guide
+Understand job states and how to track progress.
+
+## Job States
+
+| State | Description | Actions |
+|-------|-------------|---------|
+| pending | Job queued, waiting for miner | Wait |
+| assigned | Miner assigned, starting soon | Wait |
+| running | Job executing | Monitor |
+| completed | Job finished successfully | Download |
+| failed | Job error occurred | Retry/Contact |
+| canceled | Job cancelled by user | None |
+
+## Check Status
+
+### Using CLI
+
+```bash
+aitbc client status --job-id <JOB_ID>
+```
+
+### Using API
+
+```python
+import requests
+
+response = requests.get(
+    "http://localhost:8000/v1/jobs/{job_id}",
+    headers={"X-Api-Key": "your-key"}
+)
+print(response.json())
+```
+
+## Status Response Example
+
+```json
+{
+  "job_id": "job_abc123",
+  "status": "running",
+  "progress": 45,
+  "miner_id": "miner_xyz789",
+  "created_at": "2026-02-13T10:00:00Z",
+  "started_at": "2026-02-13T10:01:00Z",
+  "estimated_completion": "2026-02-13T10:30:00Z"
+}
+```
+
+## Progress Tracking
+
+### Real-time Updates
+
+```bash
+aitbc client watch --job-id <JOB_ID>
+```
+
+### WebSocket Updates
+
+```python
+import websocket
+
+def on_message(ws, message):
+    print(message)
+
+ws = websocket.WebSocketApp(
+    "ws://localhost:8000/v1/jobs/ws",
+    on_message=on_message
+)
+ws.run_forever()
+```
+
+## State Transitions
+
+```
+pending → assigned → running → completed
+    ↓           ↓          ↓
+  failed    failed     failed
+    ↓           ↓          ↓
+  canceled  canceled   canceled
+```
+
+## Next Steps
+
+- [Job Submission](./2_job-submission.md) - Submitting jobs
+- [Results](./3_job-lifecycle.md) - Managing results
+- [Job History](./3_job-lifecycle.md) - Viewing past jobs
+
+---
+Learn how to download and manage job results.
+
+## Overview
+
+Results are stored after job completion. This guide covers downloading and managing outputs.
+
+## Download Results
+
+### Using CLI
+
+```bash
+aitbc client download --job-id <JOB_ID> --output ./results
+```
+
+### Using API
+
+```python
+import requests
+
+response = requests.get(
+    "http://localhost:8000/v1/jobs/{job_id}/download",
+    headers={"X-Api-Key": "your-key"}
+)
+
+with open("output.zip", "wb") as f:
+    f.write(response.content)
+```
+
+## Result Formats
+
+| Format | Extension | Description |
+|--------|-----------|-------------|
+| JSON | `.json` | Structured data output |
+| Text | `.txt` | Plain text output |
+| Binary | `.bin` | Model weights, tensors |
+| Archive | `.zip` | Multiple files |
+
+## Result Contents
+
+A typical result package includes:
+
+```
+job_<ID>/
+├── output.json          # Job metadata and status
+├── result.txt           # Main output
+├── logs/                # Execution logs
+│   ├── stdout.log
+│   └── stderr.log
+└── artifacts/           # Model files, etc.
+    └── model.bin
+```
+
+## Result Retention
+
+| Plan | Retention |
+|------|-----------|
+| Free | 7 days |
+| Pro | 30 days |
+| Enterprise | 90 days |
+
+## Sharing Results
+
+### Generate Share Link
+
+```bash
+aitbc client share --job-id <JOB_ID>
+```
+
+### Set Expiration
+
+```bash
+aitbc client share --job-id <JOB_ID> --expires 7d
+```
+
+## Verify Results
+
+### Check Integrity
+
+```bash
+aitbc client verify --job-id <JOB_ID>
+```
+
+### Compare Checksums
+
+```bash
+# Download checksum file
+aitbc client download --job-id <JOB_ID> --checksum
+
+# Verify
+sha256sum -c output.sha256
+```
+
+## Delete Results
+
+```bash
+aitbc client delete --job-id <JOB_ID>
+```
+
+## Next Steps
+
+- [Job Status](./3_job-lifecycle.md) - Understanding job states
+- [Job Submission](./2_job-submission.md) - Submitting jobs
+- [Billing](./5_pricing-billing.md) - Understanding charges
+
+---
+View and manage your past jobs.
+
+## List All Jobs
+
+```bash
+aitbc client list
+```
+
+### Filter by Status
+
+```bash
+# Running jobs
+aitbc client list --status running
+
+# Completed jobs
+aitbc client list --status completed
+
+# Failed jobs
+aitbc client list --status failed
+```
+
+### Filter by Date
+
+```bash
+# Last 7 days
+aitbc client list --days 7
+
+# Specific date range
+aitbc client list --from 2026-01-01 --to 2026-01-31
+```
+
+## Job Details
+
+```bash
+aitbc client get --job-id <JOB_ID>
+```
+
+## Export History
+
+```bash
+# Export to JSON
+aitbc client export --format json --output jobs.json
+
+# Export to CSV
+aitbc client export --format csv --output jobs.csv
+```
+
+## Statistics
+
+```bash
+aitbc client stats
+```
+
+Shows:
+- Total jobs submitted
+- Success rate
+- Average completion time
+- Total spent
+
+## Next Steps
+
+- [Job Status](./3_job-lifecycle.md) - Understanding job states
+- [Job Cancellation](./3_job-lifecycle.md) - Canceling jobs
+- [Billing](./5_pricing-billing.md) - Understanding charges
+
+---
+How to cancel jobs and manage running operations.
+
+## Cancel a Job
+
+```bash
+aitbc client cancel --job-id <JOB_ID>
+```
+
+## Confirmation
+
+```bash
+aitbc client cancel --job-id <JOB_ID> --force
+```
+
+## Cancellation States
+
+| State | Description |
+|-------|-------------|
+| canceling | Cancellation requested |
+| canceled | Job successfully canceled |
+| failed | Cancellation failed |
+
+## Effects
+
+- Job stops immediately
+- Partial results may be available
+- Charges apply for resources used
+
+## Next Steps
+
+- [Job Submission](./2_job-submission.md) - Submitting jobs
+- [Job History](./3_job-lifecycle.md) - Viewing past jobs
+- [Pricing](./5_pricing-billing.md) - Cost structure