fix(tui): welcome splash, alt-screen, unavailable, mcp and plugins

CHANGELOG.md

@@ -10,7 +10,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Unreleased
 
 ### Changed
-- README `docs/media/intro.gif` is the signed lock TUI at 120×40 (1232×912): splash (`Cortex CLI v1.0.0`, dual hairline, violet `>`, “Plan, search, build anything”) → typing the rate-limit prompt → working (`Cortex Mini 1 · Agent`). The retired mint-mascot welcome card is gone from the banner.
+- The TUI runs **inline** by default (`alternate_screen` never). It does not enter the alternate screen on start; the real shell prompt stays in scrollback above the app. Opt in with `cortex --alternate-screen` or `[tui] alternate_screen = true`.
+- Empty-session splash is `Welcome to Cortex, the coding agent CLI` plus `v{package version} · / commands · @ files · ! shell · & cloud`. After the first user turn the splash is dropped (composer + footer only). No mascot, no painted `> cortex` shell lines.
+- Composer lock: empty is `> ` + white block at input col 0 + dim `Plan, search, build anything` after that cell (never a white rect after the placeholder). Blink-off (~530ms) hides the block so the placeholder starts at col 0. Typed copy is `#F5F5F5` with the block at the caret.
+
+### Changed
+- README `docs/media/intro.gif` is the signed lock TUI at 120×40 (1232×912): splash (`Welcome to Cortex, the coding agent CLI`, dual hairline, violet `>`, “Plan, search, build anything”) → typing the rate-limit prompt → working (`Cortex Mini 1 · Agent`). The retired mint-mascot welcome card is gone from the banner.
 - Focused composer `>` is violet `#A78BFA`; past user `>` stays white. Interrupt `× Stopped`, quota title, failed MCP `x`, and sandbox deny paint error red `#F87171`. Primary copy is `#F5F5F5`. MCP connect/drop and sandbox deny are live, not painted-only.
 - Gray chrome with one accent, replacing the violet wash: the background is still never painted (`Color::Reset`), structure comes from gray — hairlines `#3A3A3A`, filled charcoal panels `#141414`, dim `#6B7280` secondary copy, white primary copy — and the Cortex violet `#A78BFA` appears only on the focused selection (the `>` caret and the selected label on the dark gray `#262626` bar; the bar is never a violet wash). Green `#4ADE80` covers `✓` success and `+N` diff additions; red and amber stay on diagnostics; the Thinking status is a muted gold. The `#221A38` wash and the interim cyan `#7DD3FC` highlight are banned everywhere
 - The composer is the Devin-style bar in every session, working and queue state: a full-width thin gray hairline above the `> ` prompt and another below it, dim placeholder, white block cursor; it follows the transcript until the transcript fills the screen