Function detect_capabilities 

pub fn detect_capabilities(db: &Connection) -> Capabilities

Detect available capabilities by probing the database and filesystem.

Checks performed:

• fts5: items_fts virtual table present in sqlite_master
• vectors: vec_version() SQL function is callable (sqlite-vec loaded)
• semantic: MiniLM model+tokenizer files available on disk
• binary_cache: .bones/cache/events.bin exists with valid BNCH magic
• triage: items table queryable (petgraph is always compiled in)

All probes are infallible — errors are logged at debug! and treated as capability absent.

Arguments

• db — An open SQLite projection database connection.