[keys-i]

What changed

• combined the complete progression, agents, and tui branch tips into one candidate SHA
• preserved their support matrix, failure handling, export, rollback, agent, and accessible TUI contracts
• added bash run.sh --self-test to the existing Ubuntu, macOS, and Windows Python matrix

Why

The three focused PRs passed independently, but that did not prove their merged tree. This PR provides one reviewable candidate and one cross-platform check result before anything reaches main.

Validation

• every Python command self-test
• bash run.sh --self-test and bash run.sh matrix
• compact/wide TUI snapshots, keyboard flows, monochrome mode, and font fallbacks
• macOS/Linux native shell checks and available PowerShell self-test
• Ruff format/lint, Prettier 3.9.6, actionlint 1.7.12, and git diff --check

After this PR merges, #15, #16, and #17 should close as superseded rather than be merged separately.

Progresses #9.