Add a ClickHouse adapter and Model::insert_all()

[twoixter]

Summary

Adds a ClickHouse adapter for analytics workloads (ClickHouse 25.9 or later) and a bulk insert API, Model::insert_all(), that works on every adapter.

ClickHouse adapter

The adapter talks to the HTTP interface through curl, not PDO. It keeps one keep-alive connection per adapter, asks for compressed responses and sends settings as URL parameters. The minimum is 25.9 because that is the first release with lightweight UPDATE on by default.

• Results come back as TabSeparatedWithNamesAndTypes.
  • In PHP it parsed as fast as the JSON formats, and it is safe for any byte.
  • An error in the middle of a result aborts the transfer instead of looking like data.
  • The statement parses one row per fetch() and casts values from their ClickHouse type. Integers beyond PHP_INT_MAX, Int128/256 and Decimal stay strings; Array/Map/Tuple become PHP arrays.
• Binding is client-side, with literals. A ? inside quotes, quoted identifiers or comments is left alone. Numeric strings stay quoted, because an unquoted integer beyond Int64 is read as a lossy Float64.
• Errors carry the ClickHouse code. That includes errors reported after the result started streaming, in both the 25.9 format and the tagged 26.x format.
• Metadata comes from system.columns. The sorting key is not taken as the primary key, because it is not unique: the key is a column named id or the model's $primary_key. MATERIALIZED/ALIAS columns are left out.
• Keys: a UInt128 key (also Int128, UInt256, Int256, UUID or String) gets a UUIDv7 generated in PHP on insert. The new ActiveRecord\Uuid class generates them and converts between the decimal the model holds and UUID text. UInt128 sorts numerically, so ORDER BY id follows creation order; the UUID type would not.
• Dates are written as quoted Unix timestamps and read back in PHP's time zone. session_timezone is not used, because before 26.2 INSERT and lightweight UPDATE did not agree on how it applies.
• Inserts are synchronous by default. That is the fastest option per save() (about 2 ms) and errors are reported.
  • Connections can opt into async_insert=1. It keeps wait_for_async_insert=1, as ClickHouse recommends, so failed inserts are never lost silently.
  • The README compares the three modes, measured on 25.9 and 26.8, and says which one fits which insert pattern.
• Updates and deletes: update_all() and delete_all() return null, because ClickHouse does not report affected rows. DELETE without conditions gets the WHERE ClickHouse requires. Transactions throw.
• Connection URL: any other query string parameter becomes a ClickHouse setting.

Model::insert_all()

Model::insert_all($rows, ['batch_size' => N]) inserts many records with multi-row INSERT statements on MySQL, PostgreSQL, SQLite and ClickHouse.

• It builds no models, so validations and callbacks do not run.
• Aliases and inflected names are resolved, dates and JSON are converted, timestamps are filled in, and missing keys are generated as save() would generate them.
• Rows that set the same columns share statements. Batches shrink to fit the bound parameters the database accepts.
• ClickHouse writes the rows as literals and sends batches of 1000 rows or more synchronously, even on an async connection.

Core fixes

• parse_connection_url() parses the query string properly. explode('/&/') never split more than one parameter.
• Model::insert() and Table cope with tables without a primary key, instead of reading a missing pk[0].

Tests

• ClickhouseAdapterTest and ClickhouseModelTest, with their own schema (test/sql/clickhouse.sql) and models (test/models/Clickhouse). The shared fixtures rely on auto-increment keys and transactions, which ClickHouse does not have.
• InsertAllTest runs against the default adapter. UuidTest needs no database.
• CI runs ClickHouse 26.8 in every job and 25.9 in one extra row. compose.yaml has both versions.

Verified locally: 994 tests green on MySQL 5.7 and 8.4, PostgreSQL 18 and SQLite, with each of mysql, pgsql and sqlite as the default adapter, against ClickHouse 25.9 and 26.8. phpcs is clean.