chore: bootstrap Task Master with 9-task PRD breakdown

Adds the Task Master AI workspace per ~/espocrm-extensions/CLAUDE.md
convention (per-extension .taskmaster/). The PRD parses into 9 tasks
matching the 6-week implementation plan:

  #1 Windows runner + code signing infra (high)
  #2 Core services: EspoCrmClient, DPAPI, settings, logger (high)
  #3 Feature 1: File mail to case (high)
  #4 Feature 2: Reading-pane sidebar (medium)
  #5 Feature 3: Compose from case (medium)
  #6 Feature 4: Folder auto-sync (medium)
  #7 Localization + RTL (medium)
  #8 ClickOnce publish + release pipeline (high)
  #9 Documentation + rollout (high)

Config uses provider=claude-code (free) per workspace convention.
Removed task-master init's overaggressive .gitignore entries
(*.sln, *.sw?, .vscode, .idea, *.ntvs*, *.njsproj, node_modules/)
that collided with this repo's VS solution file.

Refs Task Master: see .taskmaster/tasks/tasks.json

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -54,3 +54,14 @@ desktop.ini
 .taskmaster/state.json
 .taskmaster/reports/
 .taskmaster/templates/
+
+# Task Master env / debug
+.env
+.taskmaster/dev-debug.log
+.taskmaster/npm-debug.log*
+
+# (NOTE: removed `*.sln`, `*.sw?`, `.vscode`, `.idea`, `*.ntvs*`, `*.njsproj`,
+# `node_modules/` that Task Master init added — they collide with this
+# repo's VS solution file (OutlookAddin.sln) and we don't have Node/IDE
+# directories here.)
+