Add enterprise docs structure and include pending core maintenance updates.

docs/features/storage-transactions.md

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+# Storage And Transactions
+
+## Purpose And Business Outcome
+
+Provide durable, ACID-compliant local persistence for embedded workloads that need consistent commit and recovery semantics.
+
+## Scope And Non-Goals
+
+Scope:
+- Page-based storage
+- Write-ahead logging
+- Transaction lifecycle and commit/rollback semantics
+
+Non-goals:
+- Distributed transactions
+- Multi-node replication
+
+## User And System Workflows
+
+1. Application writes through `DocumentDbContext`.
+2. Engine records WAL entries.
+3. Commit persists pages and marks transaction durable.
+4. Recovery replays WAL to restore committed state after restart.
+
+## Interfaces And APIs
+
+- `DocumentDbContext`
+- `Transaction` and `ITransaction`
+- `WriteAheadLog`
+- Storage engine modules under `src/CBDD.Core/Storage`
+
+## Permissions And Data Handling
+
+- Database files require host-managed filesystem access controls.
+- Transaction data should be treated as sensitive if payloads contain regulated information.
+
+## Dependencies And Failure Modes
+
+Dependencies:
+- Local filesystem I/O
+- WAL and page file consistency
+
+Failure modes:
+- Interrupted writes
+- Corrupted WAL entries
+- Invalid page metadata after unsafe process termination
+
+## Monitoring, Alerts, And Troubleshooting
+
+- Use CI/test failures and incident issues as primary signals.
+- Follow [`../runbook.md`](../runbook.md) for triage.
+- Follow [`../security.md`](../security.md) for data handling and control requirements.
+- Use [`../troubleshooting.md`](../troubleshooting.md#data-file-and-recovery-issues) for recovery issues.
+
+## Rollout And Change Considerations
+
+- Any storage format or WAL behavior change requires migration and rollback validation.
+- Release notes must document backward compatibility impact.
+
+## Validation Guidance
+
+- Run transaction and recovery tests in `tests/CBDD.Tests`.
+- Execute `dotnet test CBDD.slnx -c Release` before merge.