feat(tui): tuie widget-toolkit engine behind --engine tuie

Introduce a parallel TUI built on the tuie widget toolkit, selectable at
runtime with `--engine tuie`. ratatui remains the default and its
crossterm/ratatui deps are retained, so default users see no behavior
change; this lands the full screen/widget tree for the new engine
side-by-side with the existing one.

Engine wiring:
- Cargo: add `tuie` (harmonious, images features)
- main.rs: `--engine` flag + run_tuie_tui() entry path
- src/ui: new `screens`, `widgets`, `theme`, `tuie_app` modules
- app::recent_commits made pub(crate) for dashboard reuse

Screens: splash (procedural bloom), welcome dashboard, chat (live
streaming), agents picker, settings, plus cron/presence stubs.

Widgets: brand_title, portrait, menu_list, message_list, chat_bubble,
chat_input, cockpit, phase_bar, tool_card, and a reusable `responsive`
container.

Responsive welcome: the welcome screen now offers two viewable modes the
way the old ratatui dashboard did — a side-by-side portrait/stats layout
at >=100 cols and a stacked single column below it — switched by the new
`Responsive` widget. It holds both subtrees and lays out / paints only the
one that fits, while exposing both to id lookups so the menu selection
survives a resize across the breakpoint. Flourishes: a breathing title
colour pulse and a portrait border that surfaces subconscious state.
Covered by a layout test driving a TestTerminal across the breakpoint.

Cargo.lock

@@ -679,6 +679,16 @@ dependencies = [
  "fs_extra",
 ]
 
+[[package]]
+name = "axis2d"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf6c17bb125d62090a520cbb06dfe8c371252c8fb22c4588f515d0da4e51c15e"
+dependencies = [
+ "num",
+ "sign",
+]
+
 [[package]]
 name = "axum"
 version = "0.7.9"
@@ -1298,6 +1308,17 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "chord_macro"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ccfd700169d3a1973ee55dca8a659b2bde915231ecfbb1296dea2a72666bcdba"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.117",
+]
+
 [[package]]
 name = "chrono"
 version = "0.4.44"
@@ -1794,7 +1815,7 @@ dependencies = [
  "mio",
  "parking_lot",
  "rustix 0.38.44",
- "signal-hook",
+ "signal-hook 0.3.18",
  "signal-hook-mio",
  "winapi",
 ]
@@ -1812,7 +1833,7 @@ dependencies = [
  "mio",
  "parking_lot",
  "rustix 1.1.4",
- "signal-hook",
+ "signal-hook 0.3.18",
  "signal-hook-mio",
  "winapi",
 ]
@@ -5372,6 +5393,12 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "nonmax"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "610a5acd306ec67f907abe5567859a3c693fb9886eb1f012ab8f2a47bef3db51"
+
 [[package]]
 name = "noop_proc_macro"
 version = "0.3.0"
@@ -8194,9 +8221,15 @@ checksum = "47106eded3c154e70176fc83df9737335c94ce22f821c32d17ed1db1f83badb1"
 dependencies = [
  "libc",
  "os_pipe",
- "signal-hook",
+ "signal-hook 0.3.18",
 ]
 
+[[package]]
+name = "sign"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "48c0463041449de02f00a4be609a7bf85b7b4d7cb67a8e905aeaac876312b9ab"
+
 [[package]]
 name = "signal-hook"
 version = "0.3.18"
@@ -8207,6 +8240,16 @@ dependencies = [
  "signal-hook-registry",
 ]
 
+[[package]]
+name = "signal-hook"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2a0c28ca5908dbdbcd52e6fdaa00358ab88637f8ab33e1f188dd510eb44b53d"
+dependencies = [
+ "libc",
+ "signal-hook-registry",
+]
+
 [[package]]
 name = "signal-hook-mio"
 version = "0.2.5"
@@ -8215,7 +8258,7 @@ checksum = "b75a19a7a740b25bc7944bdee6172368f988763b744e3d4dfe753f6b4ece40cc"
 dependencies = [
  "libc",
  "mio",
- "signal-hook",
+ "signal-hook 0.3.18",
 ]
 
 [[package]]
@@ -8434,6 +8477,7 @@ dependencies = [
  "tracing-subscriber",
  "tui-big-text",
  "tui-widgets",
+ "tuie",
  "unicode-width 0.1.14",
  "uuid",
  "walkdir",
@@ -9510,7 +9554,7 @@ dependencies = [
  "pest_derive",
  "phf 0.11.3",
  "sha2",
- "signal-hook",
+ "signal-hook 0.3.18",
  "siphasher",
  "terminfo",
  "termios",
@@ -10203,6 +10247,23 @@ dependencies = [
  "tui-scrollview",
 ]
 
+[[package]]
+name = "tuie"
+version = "0.1.5"
+dependencies = [
+ "axis2d",
+ "base64-simd",
+ "chord_macro",
+ "image",
+ "libc",
+ "nonmax",
+ "paste",
+ "sign",
+ "signal-hook 0.4.4",
+ "unicode-display-width",
+ "unicode-segmentation",
+]
+
 [[package]]
 name = "tungstenite"
 version = "0.24.0"
@@ -10537,6 +10598,15 @@ version = "0.3.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5c1cb5db39152898a79168971543b1cb5020dff7fe43c8dc468b0885f5e29df5"
 
+[[package]]
+name = "unicode-display-width"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a43273b656140aa2bb8e65351fe87c255f0eca706b2538a9bd4a590a3490bf3"
+dependencies = [
+ "unicode-segmentation",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.24"