test: move enrichment helper unit tests

[Teagan42]

What

• move the enrichment helper unit cases from the loader suite into a dedicated tests/test_enrichment_helpers.py
• update the relocated tests to import helpers from mcp_plex.loader.pipeline.enrichment and remove the coverage from tests/test_loader_unit.py
• bump the project version metadata to 0.26.77 and refresh uv.lock

Why

• keeps the loader unit suite focused on loader behaviors while grouping enrichment-specific checks together
• aligns the tests with the helpers' module location

Affects

• test modules covering loader enrichment helpers
• project version metadata and lockfile

Testing

• uv run pytest

Documentation

• n/a

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https://chatgpt.com/codex/tasks/task_e_68e3502123d8832895e1cd970c4c54b4

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
mcp_plex/loader
__init__.py	395	18	95%	135–142, 172, 258–263, 616, 629, 748–750, 814–831, 1173
mcp_plex/loader/pipeline
__init__.py	15	7	53%	57–62, 68
channels.py	73	2	97%	19–20
enrichment.py	430	60	86%	248, 253, 284, 286, 293, 297, 376, 397, 417, 425–427, 434–437, 440–442, 450, 507, 563, 586, 590, 592, 618, 636, 648, 677, 683, 686–694, 720, 723–725, 742–744, 764–767, 771, 785–791, 813, 815, 818–820
ingestion.py	81	8	90%	67, 98–108, 129, 157, 179
orchestrator.py	85	5	94%	48, 112, 141, 164–165
persistence.py	124	9	93%	112, 154–155, 165, 170, 174–176, 214
mcp_plex/server
__init__.py	614	29	95%	43–44, 119–120, 148, 252, 256, 277–280, 297, 362, 365, 402, 420–421, 458, 1109, 1131–1137, 1173, 1191, 1196, 1214, 1338, 1375
__main__.py	4	4	0%	3–8
config.py	48	7	85%	50, 52–55, 65, 76
TOTAL	2071	149	93%

Tests	Skipped	Failures	Errors	Time
120	0 💤	0 ❌	0 🔥	53.003s ⏱️