Migrate Angular 2 to Angular 19 with standalone components

- Upgrade Angular, Firebase, and AngularFire to latest versions
- Replace NgModules with standalone components and bootstrapApplication
- Replace angular-cli.json with angular.json and ESLint
- Add Firebase App Check with reCAPTCHA v3 for abuse protection
- Move Firebase config out of version control (firebaseConfig.example.ts)
- Fix AngularFire injection context errors using runInInjectionContext
- Implement drag-and-drop reordering within and across columns
- Add inline editing for card title and description
- Add subtask deletion with confirmation modal
- Refresh UI with modern card-based look and feel

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

.gitignore

@@ -1,35 +1,45 @@
-# See http://help.github.com/ignore-files/ for more about ignoring files.
+# See https://docs.github.com/get-started/getting-started-with-git/ignoring-files for more about ignoring files.
 
-# compiled output
+# Compiled output
 /dist
 /tmp
+/out-tsc
+/bazel-out
 
-# dependencies
+# Node
 /node_modules
-/bower_components
+npm-debug.log
+yarn-error.log
 
 # IDEs and editors
-/.idea
-/.vscode
+.idea/
 .project
 .classpath
 .c9/
 *.launch
 .settings/
+*.sublime-workspace
 
-# misc
-/.sass-cache
+# Visual Studio Code
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+.history/*
+
+# Miscellaneous
+/.angular/cache
+.sass-cache/
 /connect.lock
-/coverage/*
+/coverage
 /libpeerconnection.log
-npm-debug.log
 testem.log
 /typings
 
-# e2e
-/e2e/*.js
-/e2e/*.map
+# Firebase config (contains secrets)
+src/environments/firebaseConfig.ts
 
-#System Files
+# System files
 .DS_Store
 Thumbs.db