Add LSP completion/code actions/rename/signature help infrastructure, fix TypeScript LSP, rebrand app identifiers

- LSP Layer: Add completion, completion_resolve, signature_help, code_action,
  prepare_rename, and rename methods to TextDocumentService and LspServerModel
- Types: Add CompletionItemData, CompletionResult, SignatureHelpResult,
  CodeActionData, PrepareRenameResult, RenameResult, FileEdits
- Feature Flags: Add LspCompletion, LspCodeActions, LspRename, LspSignatureHelp
- Client Capabilities: Declare completion, signature help, rename, and code
  action capabilities so servers advertise these features
- Completion UI: Add completion state machine with debounced triggers, fuzzy
  filtering, positioned overlay menu, and edit application
- TypeScript LSP: Switch to npx for running typescript-language-server (handles
  download/caching automatically, survives node version switches)
- PATH Resolution: Add interactive shell PATH fallback for LSP server discovery
  and spawning (fixes nvm/fnm/volta users)
- App Identity: Rebrand from com.samsung.Galaxy/dev.warp.WarpOss to
  samsung.galaxy.GalaxyOss across bundle IDs, URL schemes, and plists
- Add scripts/reset-galaxy.sh for clean slate testing
- Galaxy status messages and other in-progress work

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/code/editor/view.rs

@@ -1660,6 +1660,16 @@ impl CodeEditorView {
         self.model.as_ref(ctx).selections(ctx).first().head
     }
 
+    /// Returns text in the given character offset range from the buffer.
+    pub fn buffer_text_in_range(
+        &self,
+        range: Range<CharOffset>,
+        ctx: &AppContext,
+    ) -> Option<String> {
+        let buffer = self.model.as_ref(ctx).buffer().as_ref(ctx);
+        Some(buffer.text_in_range(range).into_string())
+    }
+
     pub fn hovered_symbol_range<'a>(
         &'a self,
         ctx: &'a AppContext,