30 plugins registered a DbContext and never created its tables: no migration, no
EnsureCreated, no script. Anything touching those entities failed on a fresh install,
on any database. Each now creates its schema on startup through an Umbraco migration
generated from EF's own model, and skips contexts whose tables already exist.

34 call sites also hardcoded UseSqlServer with Umbraco's connection string, so SQLite
installs — what the Umbraco installer offers by default — failed with
"Keyword not supported: 'cache'". Provider selection now follows the configured
provider name.

Failed dashboard requests now raise a notification rather than rendering an empty
state, which is what hid the earlier 401s.

Verified on a local Umbraco 17 SQLite baseline: 69 plugin tables created, 35
dashboards loading their data.