feat: add comprehensive examples across all remaining directories

Second batch of examples (65+ files):

HR Management:
- payroll-calculator: salary-calculation, tax-calculation, batch-processing
- leave-management: leave-request, balance-tracking, approval-workflow

ERP Systems:
- inventory-management: stock-operations, inventory-reports, reorder-alerts
- purchase-order-system: create-po, approval-workflow, vendor-management

Finance & Collaboration:
- expense-tracker, invoice-generator, budget-planner examples
- team-chat: messaging, knowledge-base: article-management
- video-conference: meeting-management

APIs:
- GraphQL: schema-design, resolvers, subscriptions, dataloader
- Microservices: service-communication, event-driven, circuit-breaker

Generative AI:
- openai-integration, prompt-engineering, streaming-responses
- embeddings, rag-pipeline, agent-tools, memory-management

Desktop Apps:
- Electron: ipc-communication, native-menus, file-system, system-tray, auto-updater
- Tauri: commands.rs

Browser Extensions:
- productivity: keyboard-shortcuts, data-sync
- social-media: content-extraction, ui-enhancement, download-manager
- common: background-messaging, permissions-api

Fintech:
- transaction-history, currency-conversion, risk-assessment
- compliance-check, portfolio-tracking, recurring-payments

IoT/Embedded:
- device-provisioning, data-aggregation, edge-processing
- remote-control, firmware-update, alert-system

Shared Packages:
- ui-components: form-patterns, data-table, modal-dialog
- shared-utils: api-helpers, validation-examples, security-examples, type-usage

Author: claude