[IMP] reorganize project directory structure

Restructure the project for better organization and maintainability:

New structure:
  ./upgrade.sh              - Main entry point (unchanged)
  ./lib/common.sh           - Shared bash functions
  ./lib/python/             - Python utility scripts
  ./scripts/                - Workflow scripts (prepare_db, finalize_db)
  ./config/                 - Configuration files (compose.yml)
  ./versions/{13..18}.0/    - Version-specific migration scripts

File renames:
  - pre_migration_view_checking.py -> lib/python/check_views.py
  - post_migration_fix_duplicated_views.py -> lib/python/fix_duplicated_views.py
  - post_migration_cleanup_obsolete_modules.py -> lib/python/cleanup_modules.py

Benefits:
  - Single entry point visible at root level
  - Clear separation between shared code, scripts, and config
  - Shorter, cleaner Python script names (context given by caller)
  - Easier navigation and maintenance

versions/17.0/pre_upgrade.sh

@@ -0,0 +1,57 @@
+#!/bin/bash
+set -euo pipefail
+
+echo "Prepare migration to 17.0..."
+
+# Copy database
+copy_database ou16 ou17 ou17 || exit 1
+
+# Execute SQL pre-migration commands
+PRE_MIGRATE_SQL=$(cat <<'EOF'
+DO $$
+DECLARE
+    plan_id INTEGER;
+BEGIN
+    -- Check if the 'Projects' analytic plan exists
+    SELECT id INTO plan_id FROM account_analytic_plan WHERE name = 'Projects' LIMIT 1;
+
+    -- If it doesn't exist, create it
+    IF plan_id IS NULL THEN
+        INSERT INTO account_analytic_plan (name, complete_name, default_applicability, create_date, write_date)
+        VALUES ('Projects', 'migration_PROJECTS', 'optional', now(), now())
+        RETURNING id INTO plan_id;
+    END IF;
+
+    -- Delete existing system parameter (if any)
+    DELETE FROM ir_config_parameter WHERE key = 'analytic.project_plan';
+
+    -- Insert the system parameter with the correct plan ID
+    INSERT INTO ir_config_parameter (key, value, create_date, write_date)
+    VALUES ('analytic.project_plan', plan_id::text, now(), now());
+END $$;
+EOF
+)
+echo "SQL command = $PRE_MIGRATE_SQL"
+query_postgres_container "$PRE_MIGRATE_SQL" ou17 || exit 1
+
+PRE_MIGRATE_SQL_2=$(cat <<'EOF'
+DELETE FROM ir_model_fields WHERE name = 'kanban_state_label';
+EOF
+)
+echo "SQL command = $PRE_MIGRATE_SQL_2"
+query_postgres_container "$PRE_MIGRATE_SQL_2" ou17 || exit 1
+
+PRE_MIGRATE_SQL_3=$(cat <<'EOF'
+DELETE FROM ir_model_fields WHERE name = 'phone' AND model='hr.employee';
+DELETE FROM ir_model_fields WHERE name = 'hr_responsible_id' AND model='hr.job';
+DELETE FROM ir_model_fields WHERE name = 'address_home_id' AND model='hr.employee';
+DELETE FROM ir_model_fields WHERE name = 'manager_id' AND model='project.task';
+EOF
+)
+echo "SQL command = $PRE_MIGRATE_SQL_3"
+query_postgres_container "$PRE_MIGRATE_SQL_3" ou17 || exit 1
+
+# Copy filestores
+copy_filestore ou16 ou16 ou17 ou17 || exit 1
+
+echo "Ready for migration to 17.0!"