sdk/geolocation: add Go SDK for geolocation program

[ben-dz]

Resolves: #3011

Summary of Changes

• Add a complete Go SDK for the doublezero-geolocation Solana program, providing instruction builders, state deserialization, PDA derivation, and an RPC client
• Instruction builders for all 7 program instructions: InitProgramConfig, UpdateProgramConfig, CreateGeoProbe, UpdateGeoProbe, DeleteGeoProbe, AddParentDevice, RemoveParentDevice
• Borsh-compatible state serialization/deserialization for GeolocationProgramConfig and GeoProbe accounts, with field layout matching the Rust onchain structs
• PDA derivation helpers for program config, geo probe, and program data accounts
• Transaction executor with signature polling, finalization waiting, and configurable visibility timeout
• High-level Client with read methods (GetProgramConfig, GetGeoProbeByCode, GetGeoProbes) and write methods for all instructions

Diff Breakdown

Category	Files	Lines (+/-)	Net
Core logic	12	+1192 / -0	+1192
Tests	8	+1582 / -0	+1582

All new code — 43% core logic, 57% tests.

Key files (click to expand)

• client.go — High-level SDK client with read/write methods for all geolocation accounts and instructions
• executor.go — Transaction executor with blockhash fetching, signing, submission, and finalization polling
• state.go — Borsh serialization/deserialization for GeolocationProgramConfig and GeoProbe state structs
• create_geo_probe.go — CreateGeoProbe instruction builder with validation and account metas
• update_geo_probe.go — UpdateGeoProbe instruction builder with optional fields (IP, port, metrics publisher)
• add_parent_device.go — AddParentDevice instruction builder
• remove_parent_device.go — RemoveParentDevice instruction builder with device pubkey in instruction data
• constants.go — Instruction discriminant indices, PDA seeds, and validation limits

Testing Verification

• 47 unit tests covering state roundtrip serialization, deserialization edge cases (wrong account type, truncated data, trailing bytes), all 7 instruction builders (happy path + validation errors), PDA derivation, client read methods with mock RPC, and executor error scenarios (missing signer, RPC failures, visibility timeout, finalization timeout)
• All instruction account metas and serialized args verified against the Rust onchain program source

[ben-dz]

This has been split into PR #3179 and PR#3180