feat: simplify method registry to track only planned M2/M3 operations

[h3n4l]

Summary

• Simplify method registry to track only 32 planned methods (M2: 10, M3: 22)
• New error handling design:
  • Methods IN registry → PlannedOperationError (caller should fallback to mongosh)
  • Methods NOT IN registry → UnsupportedOperationError (no fallback, just error)
• Replace DeprecatedOperationError with PlannedOperationError
• Remove Hint field from UnsupportedOperationError

This replaces the previous design that tracked deprecated/unsupported status for 297+ methods. The new design is simpler and focused on the fallback decision.

Registry Contents (32 methods)

Milestone 2 - Write Operations (10):

• insertOne, insertMany
• updateOne, updateMany, replaceOne
• deleteOne, deleteMany
• findOneAndUpdate, findOneAndReplace, findOneAndDelete

Milestone 3 - Administrative Operations (22):

• Index: createIndex, createIndexes, dropIndex, dropIndexes
• Collection: drop, renameCollection, createCollection, dropDatabase
• Database Info: stats, serverStatus, serverBuildInfo, version, hostInfo, listCommands
• Collection Info: stats, dataSize, storageSize, totalIndexSize, totalSize, isCapped, validate, latencyStats

Test plan

• go build ./... passes
• golangci-lint run passes with 0 issues
• TestPlannedOperation - verifies insertOne returns PlannedOperationError
• TestUnsupportedOperation - verifies createSearchIndex returns UnsupportedOperationError
• TestMethodRegistryStats - verifies registry contains 32 methods

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR simplifies the method registry from tracking 297+ methods with deprecated/unsupported statuses to focusing on only 32 planned methods for M2 and M3 milestones. The error handling design is streamlined: methods in the registry return PlannedOperationError (indicating fallback to mongosh is available), while methods not in the registry return UnsupportedOperationError (no fallback available).

Changes:

• Replaced DeprecatedOperationError with PlannedOperationError for clearer error semantics
• Removed Hint field from UnsupportedOperationError to simplify error structure
• Reduced method registry to 32 planned methods (10 from M2 write operations, 22 from M3 administrative operations)

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
errors.go	Replaced DeprecatedOperationError with PlannedOperationError and removed Hint field from UnsupportedOperationError
method_registry.go	Simplified registry to track only 32 planned methods; replaced complex lookup with simple IsPlannedMethod function
translator.go	Updated handleUnsupportedMethod to use new error types and simplified context handling with string literals
executor.go	Removed usage of Hint field when creating UnsupportedOperationError
executor_test.go	Updated tests to verify new error types and registry count of 32 methods

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