feat: additive security improvements — prompt guard, content filter, data classification

Prompt Injection Detection (EGAI 4.6.3.2):
- 12-pattern regex scanner on user messages before AI processing
- Logs warning + creates SecurityAlert audit entry on detection
- Reinforces system prompt instead of blocking (non-breaking)

AI Output Content Filter (EGAI 4.3.2.1):
- Scans AI responses for leaked credentials/secrets
- Auto-redacts passwords, API keys, bearer tokens, private keys
- Logs warning + SecurityAlert audit when redaction occurs

AI Tool Execution Audit Trail (IAAI 3.6.35):
- Every AI tool call creates AiToolExecution audit entry
- Logs tool name, parameters, userId, source: "ai"

Data Classification Labels (EGAI 4.2):
- DATA_CLASSIFICATION constant mapping all fields to HC/C/IR/U
- Exported from @capakraken/shared

All changes strictly additive — no existing logic modified.

Co-Authored-By: claude-flow <ruv@ruv.net>

packages/shared/src/constants/index.ts

@@ -2,6 +2,7 @@ export * from "./germanStates.js";
 export * from "./publicHolidays.js";
 export * from "./columns.js";
 export * from "./dispo-import.js";
+export * from "./data-classification.js";
 
 export const BUDGET_WARNING_THRESHOLDS = {
   INFO: 70,