feedkit: ergonomics pass (shared logger, route compiler, param helpers)

- Add logging.Logf as the canonical printf-style logger type used across feedkit.
  - Update scheduler and dispatch to alias their Logger types to logging.Logf.
  - Eliminates type-mismatch friction when wiring one log function through the system.

- Add dispatch.CompileRoutes(*config.Config) ([]dispatch.Route, error)
  - Compiles config routes into dispatch routes with event.ParseKind normalization.
  - If routes: is omitted, defaults to “all sinks receive all kinds”.

- Expand config param helpers for both SourceConfig and SinkConfig
  - Add ParamBool/ParamInt/ParamDuration/ParamStringSlice (+ Default variants).
  - Supports common YAML-decoded types (bool/int/float/string, []any, etc.)
  - Keeps driver code cleaner and reduces repeated type assertions.

- Fix Postgres sink validation error prefix ("postgres sink", not "rabbitmq sink").

logging/logging.go

@@ -0,0 +1,8 @@
+package logging
+
+// Logf is the shared printf-style logger signature used across feedkit.
+//
+// Keeping this in one place avoids the "scheduler.Logger vs dispatch.Logger"
+// friction and makes it trivial for downstream apps to pass a single log
+// function throughout the system.
+type Logf func(format string, args ...any)