fix(plugins): show a view's own definition in Show DDL and Copy DDL

[datlechin]

Why

Show DDL on a SQL Server view showed a CREATE TABLE of its columns, with an IDENTITY(1,1) the view never declared. Show DDL, Copy DDL, Structure > DDL and MCP read a view through fetchTableDDL, which only PostgreSQL and MongoDB answered for a view. The others built a fake table or failed.

Change

• SQL Server, Oracle, Dameng, DuckDB, Redshift and Cassandra show the view's own definition.
• SQLite, libSQL, D1, SAP HANA, Spanner, Trino and Teradata show it instead of failing.
• SQL Server: a renamed view shows its current name. Encrypted and unreadable views say why. An indexed view's index is written after a GO line. Edit View's fallback template names the schema.
• Oracle keeps a view's column names and reports a text over 4000 bytes instead of cutting it. Trino exports read materialized views.

Verified

New tests cover the SQL Server header and batch rules, a real SQLite view through libSQL, and HANA. The SQL Server queries ran against Azure SQL Edge, the Oracle checks against Oracle 23 Free.

Not in this PR

• The registry drivers reach users with a plugin release.
• Edit View still opens a plain CREATE VIEW on SQL Server and MySQL, which fails because the view exists.
• SQL Server table DDL still drops computed columns, identity seeds and composite foreign keys.
• Oracle lists a materialized view as a table, and its query sits in a LONG column OracleNIO cannot read.

Fixes #3402