Refactor blog module and remove blog-related functionality

- Removed blog router and associated API endpoints.
- Deleted blog persistence functions and related query parameters.
- Removed blog schemas and models from the codebase.
- Introduced common crate for shared types, including DateTimeWithTimeZoneWrapper.
- Added Thought and Follow models with corresponding migrations.
- Updated dependencies in Cargo.toml files to reflect changes.
- Adjusted tests to remove references to the blog module.

thoughts-backend/common/src/lib.rs

@@ -0,0 +1,14 @@
+use sea_orm::prelude::DateTimeWithTimeZone;
+use serde::Serialize;
+use utoipa::ToSchema;
+
+// Wrapper type for DateTimeWithTimeZone
+#[derive(Serialize, ToSchema)]
+#[schema(example = "2025-09-05T12:34:56Z")] // Example for OpenAPI
+pub struct DateTimeWithTimeZoneWrapper(String);
+
+impl From<DateTimeWithTimeZone> for DateTimeWithTimeZoneWrapper {
+    fn from(value: DateTimeWithTimeZone) -> Self {
+        DateTimeWithTimeZoneWrapper(value.to_rfc3339())
+    }
+}