Fix articles layout in guides by eliminating W3C validator warnings [ci skip]

Correct a has_many association test

Simplify `assert_no_match %r{colname.*limit:}` regex

In `test_schema_dump_includes_limit_constraint_for_integer_columns`,
unified `assert_match` and `assert_no_match` to simple regex.

Consolidate database specific JSON types to `Type::Json`

Fix `default_scoped` with defined `default_scope` on STI model

Should use `quote` for a string literal

Follow up of #29077.

Before:

```sql
SELECT sql FROM sqlite_master WHERE tbl_name NOT IN ("foo") ORDER BY tbl_name, type DESC, name
```

After:

```sql
SELECT sql FROM sqlite_master WHERE tbl_name NOT IN ('foo') ORDER BY tbl_name, type DESC, name
```

> If a keyword in double quotes (ex: "key" or "glob") is used in a
context where it cannot be resolved to an identifier but where a string
literal is allowed, then the token is understood to be a string literal
instead of an identifier.

http://www.sqlite.org/lang_keywords.html

Extract `NumericData` model for tests

Add missing `delegate :extending, to: :all`

This regression is caused by d1249c1a.

If STI model is defined `default_scope`, `base_rel` is not respected.
I fixed to merge `base_rel` in that case.

Remove a redundant test case of HABTM_associations_test

Docs: Fix output representation [ci skip]

The output of two string attributes is displayed differently in the docs. Standardize the output by always showing it as a comment.

Better spacing in environments/production.rb file

Don't expose methods and attrs for internal usage

Support PostgreSQL 10 `pg_sequence`

Another fix for #28780 based on discussions at #28789

- In PostgreSQL 10 each sequence does not know its `min_value`.
A new system catalog `pg_sequence` shows it as `seqmin`.
Refer https://github.com/postgres/postgres/commit/1753b1b027035029c2a2a1649065762fafbf63f3

- `setval` 3rd argument needs to set to `false` only when the table has no rows
to avoid `nextval(<sequence_name>)` returns `2` where `1` is expected.

- `min_value` is only necessary when the table has no rows. It used to be necessary
since the 3rd argument of `setval` is always `false`.

Remove requirement on mathn

Replace therubyracer with mini_racer

The test using mathn was first introduced in f1d91790 to check that the
`distance_of_time_in_words` properly doesn't use the `Fixnum#/` method
by explicitly requiring this library as it redefines this method.

Given that `mathn` has been gemified in Ruby 2.5 and is deprecated since
version 2.2, we can certainly safely assume that people will most-likely
not require this library in their application.

However, to make sure that we don't regress, let's add a test similar to
the one before f1d91790.

The assert_same above obviously guarantees this will pass, but this
seems less likely to be deleted just because the implementation changed.

Fix association with extension issues

Deserialize a raw value from the database in `changed_in_place?` for `AbstractJson`

Fix UUID column with `null: true` and `default: nil`

Do not use UTF8 in test SecretsCommandTest#test_edit_secrets

Bump RuboCop to 0.49.1

`quote_default_expression` can be passed nil value when `null: true` and
`default: nil`. This addressed in that case.

Fixes #29222.

[ci skip]

[ci skip]