perf(build): narrow SDK dependencies and external-source test targets

[limityan]

Summary

• replace the SDK Host product-full dependency with the explicit Core capability closure used by its current local protocol and construction path
• keep TLS initialization host-owned while removing the unused Remote Exec port binding
• consolidate runtime-free External Sources integration tests from 22 targets to 7 without merging MCP process, plugin-service, or script-runtime failure domains
• extend the existing Core boundary checker to ratchet the SDK closure and the exact reviewed test target/leaf topology

Build and dependency impact

Normal/build package-version closure for bitfun-sdk-host-app:

Target	Before	After	Delta
x86_64-pc-windows-msvc	578	512	-66
aarch64-apple-darwin	565	497	-68
x86_64-unknown-linux-gnu	609	533	-76

The current SDK protocol does not expose Remote Connect, SSH workspace execution, or Function Agent capabilities. Those owners now leave the SDK Host graph instead of being inherited through product-full. Debug Agent behavior still retains its reviewed LSP owner.

Cargo.lock is byte-identical to the base and remains at 1176 packages. This PR adds no crate, third-party package, root dependency, broad feature umbrella, workflow, CI job, or CI command. The dependency graph reduction is not presented as a measured wall-clock improvement.

Test topology

Owner	Before	After	Integration tests
OpenCode adapter	8	4	130
Claude Code adapter	4	1	51
Codex adapter	3	1	47
External Sources assembly	7	1	30
Total	22	7	258

All 19 moved test leaves are byte-for-byte moves. Runtime-free tests with identical owner, dependency, platform, and failure semantics share wrapper targets. OpenCode MCP child-process tests, managed plugin/service tests, and Node script-runtime tests remain separate. Focused execution remains available through --test <target> <module>::.

The boundary checker now locks the exact reviewed leaves and rejects Cargo required-features only on the four grouped targets. It handles bare, quoted, and Unicode-escaped TOML keys while leaving independent targets free to adopt legitimate feature gates.

Behavior and architecture

• SDK session creation continues to set remote connection and SSH metadata to None; unsupported remote execution does not fall back to local execution.
• the SDK delivery profile is documented as an explicit Core capability closure
• ring TLS provider installation remains process-entrypoint initialization and is behaviorally equivalent to the previous helper
• product-full Desktop/CLI behavior and all other product profiles are unchanged
• grouping reduces process-level crash isolation only within the four reviewed runtime-free groups; ordinary test failures remain isolated by the Rust test harness

Validation

• cargo test --offline --locked -p bitfun-sdk-host -p bitfun-sdk-host-app -p bitfun-product-capabilities -p bitfun-opencode-adapter -p bitfun-claude-code-adapter -p bitfun-codex-adapter -p bitfun-external-sources
• four grouped targets executed repeatedly, including module-filtered focused runs
• node --test scripts/check-core-boundaries.test.mjs — 79/79
• node scripts/check-core-boundaries.mjs
• three-platform cargo tree -e normal,build closure comparison
• git diff --check

Three independent adversarial review passes covered architecture/feature ownership, test semantics/failure isolation, and scope/performance evidence. Review findings around removable test leaves, hidden required-features, Unicode-escaped TOML keys, and target-level scoping were fixed and re-reviewed before publishing.