Add UX enhancements: modals for env vars and instructions, global env vars, taskbar icon fix

- Fix Windows taskbar icon by loading icon.ico instead of icon.png (ICO contains
  multiple sizes native to Windows taskbar/title bar/alt-tab)
- Add "Container must be stopped to change settings" warning banner in config panel
- Move per-project Environment Variables and Claude Instructions into modal dialogs
  for more editing space, with buttons in the config panel to open them
- Move global Claude Instructions into a modal in Settings panel
- Add default global Claude instruction recommending git initialization
- Add global environment variables support (full stack: Rust model, TS types,
  container creation with merge logic where project overrides global for same key,
  fingerprinting for recreation checks, and Settings UI with modal)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src-tauri/Cargo.lock

@@ -404,6 +404,12 @@ version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1fd0f2584146f6f2ef48085050886acf353beff7305ebd1ae69500e27c67f64b"
 
+[[package]]
+name = "byteorder-lite"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f1fe948ff07f4bd06c30984e69f5b4899c516a3ef74f34df92a2df2ab535495"
+
 [[package]]
 name = "bytes"
 version = "1.11.1"
@@ -1745,7 +1751,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3e795dff5605e0f04bff85ca41b51a96b83e80b281e96231bcaaf1ac35103371"
 dependencies = [
  "byteorder",
- "png",
+ "png 0.17.16",
 ]
 
 [[package]]
@@ -1862,6 +1868,19 @@ dependencies = [
  "icu_properties",
 ]
 
+[[package]]
+name = "image"
+version = "0.25.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6506c6c10786659413faa717ceebcb8f70731c0a60cbae39795fdf114519c1a"
+dependencies = [
+ "bytemuck",
+ "byteorder-lite",
+ "moxcms",
+ "num-traits",
+ "png 0.18.1",
+]
+
 [[package]]
 name = "indexmap"
 version = "1.9.3"
@@ -2265,6 +2284,16 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "moxcms"
+version = "0.7.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac9557c559cd6fc9867e122e20d2cbefc9ca29d80d027a8e39310920ed2f0a97"
+dependencies = [
+ "num-traits",
+ "pxfm",
+]
+
 [[package]]
 name = "muda"
 version = "0.17.1"
@@ -2280,7 +2309,7 @@ dependencies = [
  "objc2-core-foundation",
  "objc2-foundation",
  "once_cell",
- "png",
+ "png 0.17.16",
  "serde",
  "thiserror 2.0.18",
  "windows-sys 0.60.2",
@@ -2872,6 +2901,19 @@ dependencies = [
  "miniz_oxide",
 ]
 
+[[package]]
+name = "png"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60769b8b31b2a9f263dae2776c37b1b28ae246943cf719eb6946a1db05128a61"
+dependencies = [
+ "bitflags 2.11.0",
+ "crc32fast",
+ "fdeflate",
+ "flate2",
+ "miniz_oxide",
+]
+
 [[package]]
 name = "polling"
 version = "3.11.0"
@@ -3009,6 +3051,15 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "pxfm"
+version = "0.1.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7186d3822593aa4393561d186d1393b3923e9d6163d3fbfd6e825e3e6cf3e6a8"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "quick-xml"
 version = "0.38.4"
@@ -4076,6 +4127,7 @@ dependencies = [
  "gtk",
  "heck 0.5.0",
  "http",
+ "image",
  "jni",
  "libc",
  "log",
@@ -4143,7 +4195,7 @@ dependencies = [
  "ico",
  "json-patch",
  "plist",
- "png",
+ "png 0.17.16",
  "proc-macro2",
  "quote",
  "semver",
@@ -4728,7 +4780,7 @@ dependencies = [
  "objc2-core-graphics",
  "objc2-foundation",
  "once_cell",
- "png",
+ "png 0.17.16",
  "serde",
  "thiserror 2.0.18",
  "windows-sys 0.60.2",