feat: add Greenplum 7 compatibility and AI SQL generation

Greenplum 7 (PG12-based) compatibility:
- Auto-detect GP via version() string, store DbFlavor per connection
- connect returns ConnectResult with version + flavor
- Fix pg_total_relation_size to use c.oid (universal, safer on both PG/GP)
- Branch is_identity column query for GP (lacks the column)
- Branch list_sessions wait_event fields for GP
- Exclude gp_toolkit schema in schema listing, completion, lookup, AI context
- Smart StatusBar version display: GP shows "GP 7.0.0 (PG 12.4)"
- Fix connection list spinner showing on all cards during connect

AI SQL generation (Ollama):
- Add AI settings, model selection, and generate_sql command
- Frontend AI panel with prompt input and SQL output

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src-tauri/src/commands/schema.rs

@@ -1,6 +1,6 @@
 use crate::error::{TuskError, TuskResult};
 use crate::models::schema::{ColumnDetail, ColumnInfo, ConstraintInfo, IndexInfo, SchemaObject};
-use crate::state::AppState;
+use crate::state::{AppState, DbFlavor};
 use sqlx::Row;
 use std::collections::HashMap;
 use std::sync::Arc;
@@ -37,14 +37,21 @@ pub async fn list_schemas_core(
         .get(connection_id)
         .ok_or_else(|| TuskError::NotConnected(connection_id.to_string()))?;
 
-    let rows = sqlx::query(
+    let flavor = state.get_flavor(connection_id).await;
+    let sql = if flavor == DbFlavor::Greenplum {
+        "SELECT schema_name FROM information_schema.schemata \
+         WHERE schema_name NOT IN ('pg_catalog', 'information_schema', 'pg_toast', 'gp_toolkit') \
+         ORDER BY schema_name"
+    } else {
         "SELECT schema_name FROM information_schema.schemata \
          WHERE schema_name NOT IN ('pg_catalog', 'information_schema', 'pg_toast') \
-         ORDER BY schema_name",
-    )
-    .fetch_all(pool)
-    .await
-    .map_err(TuskError::Database)?;
+         ORDER BY schema_name"
+    };
+
+    let rows = sqlx::query(sql)
+        .fetch_all(pool)
+        .await
+        .map_err(TuskError::Database)?;
 
     Ok(rows.iter().map(|r| r.get::<String, _>(0)).collect())
 }
@@ -70,7 +77,7 @@ pub async fn list_tables_core(
     let rows = sqlx::query(
         "SELECT t.table_name, \
                 c.reltuples::bigint as row_count, \
-                pg_total_relation_size(quote_ident(t.table_schema) || '.' || quote_ident(t.table_name))::bigint as size_bytes \
+                pg_total_relation_size(c.oid)::bigint as size_bytes \
          FROM information_schema.tables t \
          LEFT JOIN pg_class c ON c.relname = t.table_name \
             AND c.relnamespace = (SELECT oid FROM pg_namespace WHERE nspname = $1) \
@@ -387,20 +394,28 @@ pub async fn get_completion_schema(
     state: State<'_, Arc<AppState>>,
     connection_id: String,
 ) -> TuskResult<HashMap<String, HashMap<String, Vec<String>>>> {
+    let flavor = state.get_flavor(&connection_id).await;
     let pools = state.pools.read().await;
     let pool = pools
         .get(&connection_id)
         .ok_or(TuskError::NotConnected(connection_id))?;
 
-    let rows = sqlx::query(
+    let sql = if flavor == DbFlavor::Greenplum {
+        "SELECT table_schema, table_name, column_name \
+         FROM information_schema.columns \
+         WHERE table_schema NOT IN ('pg_catalog', 'information_schema', 'pg_toast', 'gp_toolkit') \
+         ORDER BY table_schema, table_name, ordinal_position"
+    } else {
         "SELECT table_schema, table_name, column_name \
          FROM information_schema.columns \
          WHERE table_schema NOT IN ('pg_catalog', 'information_schema', 'pg_toast') \
-         ORDER BY table_schema, table_name, ordinal_position",
-    )
-    .fetch_all(pool)
-    .await
-    .map_err(TuskError::Database)?;
+         ORDER BY table_schema, table_name, ordinal_position"
+    };
+
+    let rows = sqlx::query(sql)
+        .fetch_all(pool)
+        .await
+        .map_err(TuskError::Database)?;
 
     let mut result: HashMap<String, HashMap<String, Vec<String>>> = HashMap::new();
     for row in &rows {
@@ -426,25 +441,36 @@ pub async fn get_column_details(
     schema: String,
     table: String,
 ) -> TuskResult<Vec<ColumnDetail>> {
+    let flavor = state.get_flavor(&connection_id).await;
     let pools = state.pools.read().await;
     let pool = pools
         .get(&connection_id)
         .ok_or(TuskError::NotConnected(connection_id))?;
 
-    let rows = sqlx::query(
+    let sql = if flavor == DbFlavor::Greenplum {
+        "SELECT c.column_name, c.data_type, \
+                c.is_nullable = 'YES' as is_nullable, \
+                c.column_default, \
+                false as is_identity \
+         FROM information_schema.columns c \
+         WHERE c.table_schema = $1 AND c.table_name = $2 \
+         ORDER BY c.ordinal_position"
+    } else {
         "SELECT c.column_name, c.data_type, \
                 c.is_nullable = 'YES' as is_nullable, \
                 c.column_default, \
                 c.is_identity = 'YES' as is_identity \
          FROM information_schema.columns c \
          WHERE c.table_schema = $1 AND c.table_name = $2 \
-         ORDER BY c.ordinal_position",
-    )
-    .bind(&schema)
-    .bind(&table)
-    .fetch_all(pool)
-    .await
-    .map_err(TuskError::Database)?;
+         ORDER BY c.ordinal_position"
+    };
+
+    let rows = sqlx::query(sql)
+        .bind(&schema)
+        .bind(&table)
+        .fetch_all(pool)
+        .await
+        .map_err(TuskError::Database)?;
 
     Ok(rows
         .iter()