Fix dedicated-account installation and prepare verified release candidate

[makeitfutureDev]

A fresh dedicated-account installation could inherit the operator’s container configuration and inaccessible working directory, preventing rootless image provisioning. The installer now starts runtime commands with an explicit service-account environment from the installed application directory.

This candidate also fixes image export failure propagation and recognizes exact reviewed public vendor bytes in artifact scanning. Unknown values still fail; repository files and Git history have no exceptions. Full PEM bodies are required for reviewed keys. Version/tag target is v0.6.0-rc.2; rc.1 remains immutable.

Validation:

• Real disposable Linux install/restart, encrypted synthetic backup/restore, actual CLI rollback after test and readiness failures, and uninstall: passed.
• Actual guest OS reboot, automatic systemd startup, database/container-volume persistence and uninstall: passed.
• Five focused scanner tests pass, including changed/truncated PEMs, unknown values, strict history, and stream boundaries. All 26 original public-toolchain findings were independently traced to upstream sources or byte-identical official binaries.
• Static, dependency audit and security coverage pass. Combined suite: 2185 passed, zero failures, five explicitly skipped environment/live/browser cases; 92.32% line coverage. Strict history scan passed across 3010 files/objects. Independent combined review found no critical/high issue; all six lifecycle code/workflow files match the successful hosted revision byte-for-byte. PR CI is checked before landing.

The rollback fixture controls engine smoke and npm test/pretest commands; it does not establish authenticated engine acceptance. Full live chat/provider QA is deliberately deferred, as are the existing Teams/Google Chat live cases. This prepares a draft prerelease only. The exact tagged image must still pass the full export/SBOM/scan/checksum/attestation workflow.