[pitill0]

Summary

Resolve the nine inherited mypy errors previously hidden by the --follow-imports=skip configuration.

Changes

• Add explicit selector typing for Textual runtime theme queries.
• Replace unsupported TUI style properties with supported Textual alternatives.
• Correct five TUI lifecycle checks by using App.is_running.
• Guard Web session-cookie renewal against a missing session token.
• Add regression tests covering TUI updates while the application is inactive.

Validation

• Official make gate: PASS
• Pytest: 1,565 passed, 7 skipped
• Full mypy (mypy --no-incremental fluxtuner/): 0 errors across 106 files
• Ruff format and lint: PASS
• JavaScript syntax validation: PASS
• pip-audit: no known vulnerabilities
• Bandit: no issues identified
• Real Textual lifecycle probe: PASS

Scope

Four files changed. No dependency, public API, database schema or packaging changes.

Follow-up

Evaluate enabling full mypy checking in the official Makefile gate in a separate change, so future type errors cannot be hidden by import skipping.