feat: implement remaining M3 administrative commands

[h3n4l]

Summary

• Add 15 remaining M3 commands via RunCommand and Go driver APIs:
  • Database info: db.stats(), db.serverStatus(), db.serverBuildInfo(), db.version(), db.hostInfo(), db.listCommands()
  • Collection info: collection.stats(), collection.dataSize(), collection.storageSize(), collection.totalIndexSize(), collection.totalSize(), collection.isCapped()
  • Collection admin: collection.validate(), collection.latencyStats()
  • Index management: collection.createIndexes()
• Empties the method registry so all commands execute natively without mongosh fallback
• This completes the full M3 milestone

Test plan

• All new commands have integration tests in admin_test.go
• Unit tests pass: go test ./internal/...
• go vet ./... passes
• Test binary compiles: go test -c -o /dev/null .

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Implements the remaining M3 administrative/metadata commands end-to-end (parser translation → operation types → executor implementations) and adds integration coverage for them.

Changes:

• Added new operation types and wired translator visitor cases for remaining DB/collection admin commands (including createIndexes, stats/info commands, validate, latencyStats).
• Implemented executor support via RunCommand, collStats, aggregation $collStats, and Go driver index APIs.
• Added integration tests in admin_test.go for the new commands and removed all “planned/fallback” entries from the method registry.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
types/operation_type.go	Adds new OperationType constants for M3 admin/info commands.
internal/translator/visitor.go	Routes new parsed commands/method calls to the new operation types.
internal/translator/types.go	Extends Operation with IndexSpecs for createIndexes().
internal/translator/method_registry.go	Clears planned-method registry (no more mongosh fallback for M1–M3).
internal/translator/collection.go	Adds argument extraction for createIndexes() specs.
internal/executor/executor.go	Dispatches new operation types to executor implementations.
internal/executor/admin.go	Implements createIndexes plus DB/collection info/admin commands.
client.go	Documents result shapes for the new operations.
admin_test.go	Adds integration tests for all newly implemented commands.

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