feat(telegram): add sugared wrapper for takeout sessions

[majiayu000]

Fixes #1332

Changes

• Add telegram/takeout package with Client wrapper that implements tg.Invoker
• Client.Invoke automatically wraps calls with InvokeWithTakeoutRequest
• Add Run function to manage takeout session lifecycle (init, callback, cleanup)
• Add Config struct for configuring takeout session options (contacts, messages, files, etc.)

[codecov]

Codecov Report

❌ Patch coverage is 89.74359% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.86%. Comparing base (0535561) to head (6c50a9f).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
telegram/takeout/takeout.go	89.74%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1660      +/-   ##
==========================================
- Coverage   69.02%   68.86%   -0.16%     
==========================================
  Files         446      447       +1     
  Lines       18407    18446      +39     
==========================================
- Hits        12705    12703       -2     
- Misses       4760     4807      +47     
+ Partials      942      936       -6     

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