refactor!: remove Go SDK (closes #481)

[userFRM]

Summary

Removes the Go SDK entirely. The cgo bridge between Rust's C ABI and Go's runtime carries per-call overhead that masks the upstream throughput this SDK is engineered for. Users who need Go bindings can build their own cgo wrapper against the unchanged C ABI in crates/ffi/ — header at sdks/cpp/include/thetadx.h, all FFI types and free fns exported as tdx_* symbols.

What was deleted

Surface	Count
sdks/go/ source files	30
crates/thetadatadx/build_support/ Go modules + templates	18 (5 .rs, 13 .tmpl)
tick_schema.toml Go-prefixed render rows (go_struct, go_converter)	32
sdk_surface.toml Go target entries (go_fpss, go)	23 method/utility targets + the entire [[go_ffi.tls_reader_markers]] block (5 entries)
CI workflow jobs / steps removed	live.yml: 3 cgo blocks + 3 setup-go setups; ci.yml: setup-go setups + the go test ./... block in sdk-bindings
dependabot.yml Go module entry	1
.gitattributes sdks/go/ rules	10
Tracked *_go*.rs source files	0 remaining

Net change: 113 files touched, ~310 insertions, ~11,777 deletions.

The shared (size, align, offset) math previously living in ticks/go.rs (used by the C++ static-assert emitter and tdbe layout-guard emitter) was extracted into a neutral crates/thetadatadx/build_support/ticks/layout.rs module — neither emitter is Go-specific, the helper just happened to live there for historical reasons.

Supported integration path going forward

The C ABI in crates/ffi/ is unchanged. Third-party cgo / Swift / Zig / Nim / etc. wrappers continue to work against the same extern "C" surface. Header at sdks/cpp/include/thetadx.h. The TypeScript and Python SDKs continue to ship as pre-built binaries (napi-rs and PyO3 abi3).

Validation

Local CI gate (all clean):

• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test --workspace
• cargo deny check — advisories, bans, licenses, sources all ok
• cargo run -p thetadatadx --bin generate_sdk_surfaces --features config-file -- --check — no drift
• cargo check --manifest-path tools/mcp/Cargo.toml --locked
• cargo clippy --manifest-path tools/mcp/Cargo.toml --all-targets -- -D warnings
• cargo test --manifest-path tools/mcp/Cargo.toml --no-run
• cargo check --manifest-path tools/server/Cargo.toml --locked
• cargo check --manifest-path sdks/python/Cargo.toml --locked
• cargo check --manifest-path sdks/typescript/Cargo.toml --locked

Test plan

• Confirm the Surfaces job is green on CI (it now skips the Go bindings step entirely).
• Confirm SDK Bindings job still builds the C++ artifact across Linux / macOS / Windows from the FFI artifact.
• Spot-check the regenerated frames_generated.rs, tick_classes.rs (Python + TS), and fpss_event_structs.h.inc (C++) — their content must come from the SSOT only.

Closes #481.