feat(graph): introduce graph.inspect.v1 contract and schema for SBOM relationships

- Added graph.inspect.v1 documentation outlining payload structure and determinism rules.
- Created JSON schema for graph.inspect.v1 to enforce payload validation.
- Defined mapping rules for graph relationships, advisories, and VEX statements.

feat(notifications): establish remediation blueprint for gaps NR1-NR10

- Documented requirements, evidence, and tests for Notifier runtime.
- Specified deliverables and next steps for addressing identified gaps.

docs(notifications): organize operations and schemas documentation

- Created README files for operations, schemas, and security notes to clarify deliverables and policies.

feat(advisory): implement PostgreSQL caching for Link-Not-Merge linksets

- Created database schema for advisory linkset cache.
- Developed repository for managing advisory linkset cache operations.
- Added tests to ensure correct functionality of the AdvisoryLinksetCacheRepository.

src/Concelier/__Libraries/StellaOps.Concelier.Storage.Postgres/Migrations/002_lnm_linkset_cache.sql

@@ -0,0 +1,21 @@
+-- Link-Not-Merge linkset cache (PostgreSQL)
+-- Stores deterministic cache entries for advisory linksets per tenant/source/advisory.
+
+CREATE TABLE IF NOT EXISTS vuln.lnm_linkset_cache (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id TEXT NOT NULL,
+    source TEXT NOT NULL,
+    advisory_id TEXT NOT NULL,
+    observations TEXT[] NOT NULL DEFAULT '{}',
+    normalized JSONB,
+    conflicts JSONB,
+    provenance JSONB,
+    confidence DOUBLE PRECISION,
+    built_by_job_id TEXT,
+    created_at TIMESTAMPTZ NOT NULL,
+    CONSTRAINT uq_lnm_linkset_cache UNIQUE (tenant_id, advisory_id, source)
+);
+
+CREATE INDEX IF NOT EXISTS idx_lnm_linkset_cache_order
+    ON vuln.lnm_linkset_cache (tenant_id, created_at DESC, advisory_id, source);
+