[joepetjr]

What

Removes the unused blog metadata generator (unit U14, part 1 of 2; part 2 removes the blog and Twitter adapters and is stacked on this branch).

• Deleted seo_manager/generation/blog_generator.py (427 lines) and tests/unit/test_blog_generator.py (424 lines).
• SEOManager._get_generator no longer has the Platform.BLOG branch that imported it; a non-YouTube platform falls through to BaseSEOGenerator, as before for every other platform.
• Dropped the BlogMetadataGenerator export from seo_manager/generation/__init__.py; reworded the one comment in youtube_generator.py that cited the blog generator.
• Dropped the one blog golden case in test_title_length_constraint.py that asserted the blog generator's ": Overview" padding.
• ARCHITECTURE.md "Adding New Generators" example no longer uses BlogMetadataGenerator as its sample; CHANGELOG Removed entry added.
• New tests/unit/test_removed_blog_generator.py keeps the module, file and class name from coming back.

Nothing calls it

On origin/main (662cbe9), git grep -nE "blog_generator|BlogMetadataGenerator" outside the two deleted files finds only: core/manager.py:177,179 (the branch removed here), generation/__init__.py:9,15 (the export removed here) and the ARCHITECTURE.md:343 example (reworded here). The CLI and the daemon only drive YouTube. After this change the same grep finds only the new guard test. No console templates, config files or docs reference it.

Tests

• Full suite: 1481 passed, 19 xfailed, 2 xpassed (log: exec/logs/B1-pytest.log in the author's scratchpad), coverage 88.72% against the 66% floor.
• ruff check . and ruff format --check . clean at the CI pin.
• Diff: 37 insertions, 867 deletions (904 sum).

Order

Based on main. The adapters PR (stacked) is based on this branch.