fix(Mountain): Remove duplicate DevTools window in debug builds

WindowBuild.rs was calling `MainWindow.open_devtools()` independently
from AppLifecycle.rs, causing two DevTools windows to open on every
debug launch. Remove the redundant call and document that DevTools
auto-open lives in AppLifecycle (line 174), gated on debug_assertions
with a matching log line.

docs(Mountain): Clarify diagnostic coordinates are 1-based

Update DiagnosticProvider.rs docstring to specify that
StartLineNumber/StartColumn and EndLineNumber/EndColumn use 1-based
indexing, matching workbench IMarkerData. Add note explaining that
Cocoon's LanguagesNamespace.ts NormaliseDiagnostic adds the +1 offset
from vscode.Position 0-based convention before sending to Mountain.

Author: NikolaRHristov

Source/Binary/Build/WindowBuild.rs

@@ -94,11 +94,12 @@ pub fn WindowBuild(Application:&mut App, LocalhostUrl:String) -> tauri::WebviewW
 	// Build the main window
 	let MainWindow = WindowBuilder.build().expect("FATAL: Main window build failed");
 
-	// Open DevTools in debug builds
-	#[cfg(debug_assertions)]
-	{
-		MainWindow.open_devtools();
-	}
+	// DevTools auto-open lives in `Binary/Main/AppLifecycle.rs:174`
+	// (gated on `cfg(debug_assertions)`, with a `[Window] Debug build:
+	// opening DevTools.` log line). Calling `open_devtools()` here as
+	// well opened a SECOND DevTools window on every debug launch -
+	// reported as "two DevTools" after the last rebuild. Single-source
+	// the call to AppLifecycle so the log line and the window match.
 
 	MainWindow
 }

Source/Environment/DiagnosticProvider.rs

@@ -74,8 +74,11 @@
 //! Each diagnostic is a `MarkerDataDTO`:
 //! - `Severity`: Error(8), Warning(4), Information(2), Hint(1)
 //! - `Message`: Human-readable description
-//! - `StartLineNumber`/`StartColumn`: Start position (0-based)
-//! - `EndLineNumber`/`EndColumn`: End position
+//! - `StartLineNumber`/`StartColumn`: Start position (1-based, matches
+//!   workbench `IMarkerData` - Cocoon's `LanguagesNamespace.ts`
+//!   `NormaliseDiagnostic` adds the `+ 1` from vscode.Position 0-based
+//!   before sending to Mountain)
+//! - `EndLineNumber`/`EndColumn`: End position (1-based, same convention)
 //! - `Source`: Diagnostic source string (e.g., "tslint")
 //! - `Code`: Diagnostic code for quick fix lookup
 //! - `ModelVersionIdentifier`: Document version for tracking