Add external dependencies CI/CD pipelines with SBOM generation

- Create external-dependencies directory structure with per-package pipelines
- Add DEPENDENCIES-INVENTORY.md with comprehensive dependency tracking
- Create ubuntu-26.04-build-container base image with all dependencies
- Add per-package Jenkinsfiles: log4qt, grantlee, googletest, postgresql, qt6-framework, kdreports
- Add SBOM generation script (generate-sbom.sh) for CycloneDX, SLSA v1.0, and license reports
- Integrate SBOM generation into all Jenkins pipelines
- Add external-dependencies/README.md with usage and security documentation
- Exclude proprietary license files (rti_license.dat) from git tracking

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Entire-Checkpoint: 01M6KNFNMSPW4SY4J4SQTTPVBP

external-dependencies/postgresql/README.md

@@ -0,0 +1,28 @@
+# PostgreSQL
+
+PostgreSQL client libraries installation pipeline.
+
+## Version
+
+- **PostgreSQL:** 16 (Ubuntu 26.04 default)
+- **Package:** libpq-dev
+- **License:** PostgreSQL License
+
+## Installation
+
+```bash
+apt-get update
+apt-get install -y libpq-dev postgresql-client
+```
+
+## Verification
+
+```bash
+psql --version
+```
+
+## SBOM
+
+- `sbom/postgresql-16-sbom.json`
+- `sbom/postgresql-16-provenance.json`
+- `sbom/postgresql-16-licenses.md`