build: migrate to tui-realm 4.0

[veeso]

Summary

• Upgrade tuirealm (3.x → 4.0), tui-realm-stdlib (3 → 4) and tui-term (0.2 → 0.3)
• Apply all breaking changes from the tui-realm 4.0 migration guide across termscp's UI (78 files)
• Make Theme deserialization backwards compatible so pre-existing theme files keep working

Migration highlights

• Root-level re-exports removed → module-qualified imports (tuirealm::application, component, event, props, state, subscription, listener, ratatui; tui_realm_stdlib::components::*)
• MockComponent → Component; old Component trait → AppComponent; fn on now takes &Event<_>; #[derive(Component)] replaces #[derive(MockComponent)]
• TextSpan → SpanStatic/LineStatic/TextStatic; (String, Alignment) titles → Title builder; Alignment split into HorizontalAlignment/VerticalAlignment; stdlib components use .alignment_horizontal
• State::One/PropPayload::One → Single; CmdResult::None → NoChange; Props::get_or removed and Props::get now borrows; Component::query returns Option<QueryResult<'a>>
• Attribute::HighlightedColor → HighlightStyle (full Style); .highlighted_* helpers → .highlight_*
• PollStrategy::UpTo(n) now requires a Duration; tick timeout moved from EventListenerCfg::poll_timeout into PollStrategy
• TerminalBridge removed → Context now owns a CrosstermTerminalAdapter directly
• Update trait removed → activity update methods are plain inherent functions
• stdlib ProgressBar → Gauge; Paragraph .wrap → .wrap_trim; .text now takes Into<Text>; stdlib List rows are Vec<Span> per row (custom FileList/Log convert between the old Table model and the new one)

UX fixes needed after the migration

• Radio builders drop .foreground(color) so unselected entries use the terminal default foreground, and set highlight_style(Style::default().fg(color).add_modifier(REVERSED)) so only the selected entry is colored
• Custom FileList keeps the full highlight style on the selected row when focused, and falls back to a foreground-only style when unfocused
• Borders use stdlib defaults on blur (no .inactive override), keeping the unfocused fg at terminal default

Theme backwards compatibility

Theme now uses a custom Deserialize through an intermediate ThemeFile with optional string fields. Missing fields, unknown values or legacy aliases (transfer_progress_bar_full/_partial) fall back to defaults on a per-field basis instead of failing the whole theme load. Covered by new tests in src/config/themes.rs and an updated expectation in src/config/serialization.rs.

Test plan

• cargo build --no-default-features
• cargo clippy --no-default-features -- -Dwarnings
• cargo +nightly fmt --all -- --check
• cargo test --no-default-features --features github-actions --no-fail-fast
• Manual: auth activity (forms, bookmarks, protocol radio colors)
• Manual: file transfer activity (focus/blur on file lists, popups, progress bar)
• Manual: setup activity (config/theme/ssh tabs)
• Manual: verify an existing theme file (including one with legacy transfer_progress_bar_* or malformed colors) still loads and applies saved colors

[cocogitto-bot]

✔️ 7fde801 - Conventional commits check succeeded.