Add unit and integration tests for VexCandidateEmitter and SmartDiff repositories

- Implemented comprehensive unit tests for VexCandidateEmitter to validate candidate emission logic based on various scenarios including absent and present APIs, confidence thresholds, and rate limiting.
- Added integration tests for SmartDiff PostgreSQL repositories, covering snapshot storage and retrieval, candidate storage, and material risk change handling.
- Ensured tests validate correct behavior for storing, retrieving, and querying snapshots and candidates, including edge cases and expected outcomes.

docs/advisory-ai/architecture.md

@@ -27,7 +27,7 @@ Conseiller / Excititor / SBOM / Policy
             v
    +----------------------------+
    | Cache & Provenance          |
-   |   (Mongo + DSSE optional)   |
+   |   (PostgreSQL + DSSE opt.)  |
    +----------------------------+
             |                 \
             v                  v
@@ -48,7 +48,7 @@ Key stages:
 | `AdvisoryPipelineOrchestrator` | Builds task plans, selects prompt templates, allocates token budgets. | Tenant-scoped; memoises by cache key. |
 | `GuardrailService` | Applies redaction filters, prompt allowlists, validation schemas, and DSSE sealing. | Shares configuration with Security Guild. |
 | `ProfileRegistry` | Maps profile IDs to runtime implementations (local model, remote connector). | Enforces tenant consent and allowlists. |
-| `AdvisoryOutputStore` | Mongo collection storing cached artefacts plus provenance manifest. | TTL defaults 24h; DSSE metadata optional. |
+| `AdvisoryOutputStore` | PostgreSQL table storing cached artefacts plus provenance manifest. | TTL defaults 24h; DSSE metadata optional. |
 | `AdvisoryPipelineWorker` | Background executor for queued jobs (future sprint once 004A wires queue). | Consumes `advisory.pipeline.execute` messages. |
 
 ## 3. Data contracts

docs/advisory-ai/overview.md

@@ -20,7 +20,7 @@ Advisory AI is the retrieval-augmented assistant that synthesises Conseiller (ad
 | Retrievers | Fetch deterministic advisory/VEX/SBOM context, guardrail inputs, policy digests. | Conseiller, Excititor, SBOM Service, Policy Engine |
 | Orchestrator | Builds `AdvisoryTaskPlan` objects (summary/conflict/remediation) with budgets and cache keys. | Deterministic toolset (AIAI-31-003), Authority scopes |
 | Guardrails | Enforce redaction, structured prompts, citation validation, injection defence, and DSSE sealing. | Security Guild guardrail library |
-| Outputs | Persist cache entries (hash + context manifest), expose via API/CLI/Console, emit telemetry. | Mongo cache store, Export Center, Observability stack |
+| Outputs | Persist cache entries (hash + context manifest), expose via API/CLI/Console, emit telemetry. | PostgreSQL cache store, Export Center, Observability stack |
 
 See `docs/modules/advisory-ai/architecture.md` for deep technical diagrams and sequence flows.