feat(dev-server): Use tablesSchemaV2 in playground/db-schema endpoint

[igorlukanin]

It will also fetch info about primary and foreign keys.

Check List

• Tests have been run in packages where changes have been made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Issue Reference this PR resolves

Resolves #10228

Conversation with Claude

claude.txt

[Copilot]

Pull request overview

This PR enhances the /playground/db-schema endpoint to fetch additional metadata about primary and foreign keys by switching from tablesSchema() to tablesSchemaV2().

• Updates the dev server's database schema endpoint to use the V2 method that includes primary and foreign key information
• Maintains backward compatibility since tablesSchemaV2() returns the same structure as tablesSchema() but with enhanced metadata

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 55.17%. Comparing base (df8161c) to head (e82f2b9).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
packages/cubejs-server-core/src/core/DevServer.ts	0.00%	1 Missing ⚠️

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HEAD has 1 upload less than BASE

Flag	BASE (df8161c)	HEAD (e82f2b9)
cubesql	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #10275       +/-   ##
===========================================
- Coverage   83.27%   55.17%   -28.11%     
===========================================
  Files         248      221       -27     
  Lines       74448    17202    -57246     
  Branches        0     3521     +3521     
===========================================
- Hits        61999     9491    -52508     
+ Misses      12449     7216     -5233     
- Partials        0      495      +495     

Flag	Coverage Δ
cube-backend	55.17% <0.00%> (?)
cubesql	?

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