[xoolive]

Summary

Add an interactive Sources panel toggled with s/S, alongside the aircraft table:

• display source aliases/stable IDs, connection states and latest retained failure reasons;
• preserve search input, the error overlay and unread-error counts;
• render a consistent health snapshot outside the health mutex and cap panel height at half the terminal;
• hide stale failure reasons after recovery and avoid empty-aircraft navigation overflow;
• give SeRo subscriptions recognizable opaque labels and report readiness before the first frame, attributed failures/EOF, and disabled-feature errors without logging credentials.

Also restore compatibility needed to launch existing configurations: boolean prevent_sleep values, optional CLI sleep flags, and contextual default-config errors rather than a panic dumping the full TOML.

SeRo capture-clock selection is deliberately not included: it follows in stacked draft #550, where timing observations and remaining issues will be discussed. This PR does not change Beast/RTL-SDR timestamps, CPR rules or Tangram.

Validation of this exact commit tree

Exported the staged tree without local/untracked files, then passed:

• cargo fmt --all --check
• cargo test --locked --workspace --all-features --all-targets — 145 tests
• cargo clippy --locked --workspace --all-features --all-targets -- -D warnings
• rs1090/Jet1090 no-default-feature tests and strict Clippy
• workspace doctests and strict rustdoc

Tests cover keyboard/search isolation, source states/recovery, an empty registry, aircraft-table preservation and tiny terminal/panel combinations. SeRo tests are offline; no user configuration, token, capture data or local integration-test file is included.

No version bump, release or merge is requested.