fix: load complete items and send TMDb auth header

[Teagan42]

What

• treat added_at as datetime
• ensure full metadata by fetching items from Plex
• send TMDb API key via bearer token

Why

• Plex addedAt is a datetime
• LibrarySection.all() returns partial items
• TMDb now expects auth in the Authorization header

Affects

• loader
• type definitions
• tests

Testing

• uv run ruff check .
• uv run pytest

Documentation

• none

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https://chatgpt.com/codex/tasks/task_e_68c64199665c8328906e27b39b0410f9

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
mcp_plex
loader.py	197	10	95%	32–34, 331, 334–338, 663
server.py	304	21	93%	86, 104–105, 227, 455, 459, 479–483, 515, 525, 556–557, 574–575, 598, 601–602, 661
TOTAL	605	31	95%

Tests	Skipped	Failures	Errors	Time
29	0 💤	0 ❌	0 🔥	28.400s ⏱️