One window, the app's own page; the server through /api/v2

The two webviews (local title bar, remote web UI) become one WebviewWindow on
ui/index.html. The window refuses every navigation but the app's page and its
sealed frames; the capability still names only main and no remote URL.

- server.rs: discovery refuses a server older than 2.0 (protocol 3 and major
  version 2) and an app API newer than this app knows; the app's own device
  login for the app scope, the token kept in account.json (0600) and never
  given to the page; a proxy limited to /api/v2 paths; the SSE stream.
- files.rs: list and read the agent's working directory, resolved (links and
  .. included) and refused outside the agent's folders.
- sealed.rs: HTML for the viewer on its own scheme under the server's sealed
  policy: no bridge, no network, no navigation.
- watch.rs + tauri-plugin-notification: a notification when a reply or an
  agent chat finishes out of sight.
- A failed start and panics go to desktop.log; a missing tray no longer stops
  the app; the DMA-BUF renderer is off under NVIDIA's driver.
- The unstable multiwebview feature, the gtk dependency and the theme report
  are gone.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src-tauri/Cargo.lock

@@ -469,6 +469,17 @@ version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4e7648175b45a9a48536d676f68d918270699102aa8dab5496df06904c914600"
 
+[[package]]
+name = "chacha20"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "65c35e4b699c7e15ccbe7ee35c005e4fc0a278d22238a2857e6ce2dadeda1b06"
+dependencies = [
+ "cfg-if",
+ "cpufeatures 0.3.1",
+ "rand_core",
+]
+
 [[package]]
 name = "chrono"
 version = "0.4.45"
@@ -569,6 +580,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "cpufeatures"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5ca28b0ae3115b884660db4118d803791fd6756b6e88f39c0f3f7859060d7566"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "crc32fast"
 version = "1.5.2"
@@ -1296,6 +1316,7 @@ dependencies = [
  "cfg-if",
  "libc",
  "r-efi 6.0.0",
+ "rand_core",
 ]
 
 [[package]]
@@ -2066,13 +2087,13 @@ checksum = "47d9d19d1d6efa0109d2f65ff4c85cddd50bd572e5a00127ab10987290bcefae"
 name = "llembas-desktop"
 version = "0.7.2"
 dependencies = [
- "gtk",
  "libc",
  "serde",
  "serde_json",
  "tauri",
  "tauri-build",
  "tauri-plugin-dialog",
+ "tauri-plugin-notification",
  "tauri-plugin-opener",
  "tauri-plugin-single-instance",
  "tauri-plugin-updater",
@@ -2094,6 +2115,20 @@ version = "0.4.34"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f9f8bd3e56ce4dfc153cf470fffbfa98c7620958b312ca5c3a4b8d5181fd13c6"
 
+[[package]]
+name = "mac-notification-sys"
+version = "0.6.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd604973958ddcc11b561193c0fb96ba146506ef2f231ef2e7c35fd2cbc9beca"
+dependencies = [
+ "cc",
+ "log",
+ "objc2",
+ "objc2-foundation",
+ "time",
+ "uuid",
+]
+
 [[package]]
 name = "markup5ever"
 version = "0.39.0"
@@ -2220,6 +2255,20 @@ version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "650eef8c711430f1a879fdd01d4745a7deea475becfb90269c06775983bbf086"
 
+[[package]]
+name = "notify-rust"
+version = "4.18.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4587364a9a0074333429b3df75a30a205340c56a536ca3eb6ca0e59b87bbf8af"
+dependencies = [
+ "futures-lite",
+ "log",
+ "mac-notification-sys",
+ "serde",
+ "tauri-winrt-notification",
+ "zbus",
+]
+
 [[package]]
 name = "num-conv"
 version = "0.2.2"
@@ -2842,6 +2891,23 @@ version = "6.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f8dcc9c7d52a811697d2151c701e0d08956f92b0e24136cf4cf27b57a6a0d9bf"
 
+[[package]]
+name = "rand"
+version = "0.10.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "65c9fb96cbc91e3478eaae79a69fcd3f1ae4ad052e471fe6732fff548984b4af"
+dependencies = [
+ "chacha20",
+ "getrandom 0.4.3",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "63b8176103e19a2643978565ca18b50549f6101881c443590420e4dc998a3c69"
+
 [[package]]
 name = "raw-window-handle"
 version = "0.6.2"
@@ -3429,7 +3495,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a7507d819769d01a365ab707794a4084392c824f54a7a6a7862f8c3d0892b283"
 dependencies = [
  "cfg-if",
- "cpufeatures",
+ "cpufeatures 0.2.17",
  "digest",
 ]
 
@@ -3925,6 +3991,26 @@ dependencies = [
  "url",
 ]
 
+[[package]]
+name = "tauri-plugin-notification"
+version = "2.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5bc6c194a95a535abdfbe3bc1af9a43935b8b9b29c216b8e71af8b59132703cf"
+dependencies = [
+ "log",
+ "notify-rust",
+ "rand",
+ "serde",
+ "serde_json",
+ "serde_repr",
+ "tauri",
+ "tauri-plugin",
+ "thiserror 2.0.21",
+ "time",
+ "url",
+ "zbus",
+]
+
 [[package]]
 name = "tauri-plugin-opener"
 version = "2.7.1"
@@ -4097,6 +4183,17 @@ dependencies = [
  "toml 1.1.8+spec-1.1.0",
 ]
 
+[[package]]
+name = "tauri-winrt-notification"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f37a6c354fd28fc9e322ed9bd47e3959576dad28c9d58ea1cf888cce1c7ccb36"
+dependencies = [
+ "thiserror 2.0.21",
+ "windows",
+ "windows-version",
+]
+
 [[package]]
 name = "tempfile"
 version = "3.27.0"