chore(wailsv3): add v3 Taskfile build scaffolding and config

Desktop-Linux-only scaffolding adapted from the stock v3 svelte template; no mobile taskfiles added yet.

- Taskfile.yml (root): APP_NAME AniTrack, BIN_DIR build/bin (keeps the v2 output path so release packaging is untouched), includes common+linux only, build/run/dev tasks.
- build/Taskfile.yml: stock common tasks (frontend build, bindings regen, go mod tidy).
- build/linux/Taskfile.yml: stock, minus the common:generate:icons dep (it targets macOS/Windows icons from a build/appicon.png this project does not have; icons ship via build/icon + the release tarball). Generated build/linux/AniTrack.desktop committed (stable output).
- build/config.yml: AniTrack metadata, version 1.6.8. NOTE: ./release only bumps wails.json productVersion, not this file - bump both on release until the script learns about it.
- wails.json: v3 frontend block (dir/install/build/dev/devServerUrl :5173); author + info.productVersion kept for the in-app title and the release version guard.
- Makefile: wails dev/build -> wails3 dev -port 5173 / wails3 build. The v2 webkit2_41 tag is a v2-ism v3 ignores; v3 defaults to GTK4/WebKitGTK 6.0 (same 2.52.x engine generation), so no tags.
- .gitignore: task cache dir .task/ ignored.

build/config.yml

@@ -0,0 +1,42 @@
+# Wails v3 project configuration.
+# NOTE: `info.version` is informational only. The release flow (`./release`,
+# `make release`) bumps `wails.json` -> info.productVersion and does NOT touch
+# this file, so bump both together when cutting a release.
+version: '3'
+
+info:
+  companyName: "John O'Keefe"
+  productName: "AniTrack"
+  productIdentifier: "com.linuxhg.anitrack"
+  description: "Track anime watchlists across AniList, MyAnimeList, and Simkl"
+  copyright: "John O'Keefe"
+  version: "1.6.8"
+
+# Dev mode configuration
+dev_mode:
+  root_path: .
+  log_level: warn
+  debounce: 1000
+  ignore:
+    dir:
+      - .git
+      - node_modules
+      - frontend
+      - bin
+    file:
+      - .DS_Store
+      - .gitignore
+      - .gitkeep
+      - "*_test.go"
+    watched_extension:
+      - "*.go"
+      - "*.js"
+      - "*.ts"
+    git_ignore: true
+  executes:
+    - cmd: wails3 build DEV=true
+      type: blocking
+    - cmd: wails3 task common:dev:frontend
+      type: background
+    - cmd: wails3 task run
+      type: primary