refactor(tools): move generic runtime assembly contracts

[limityan]

Summary

• Delegate generic static-provider runtime assembly, decorator references, snapshot decorator adapter, and readonly/enabled registry filtering to bitfun-agent-tools.
• Keep product-owned provider groups, snapshot wrapper integration, ToolUseContext, runtime manifest facade, and GetToolSpec execution in bitfun-core.
• Update boundary checks and decomposition docs so the next H1 step is limited to ToolUseContext, runtime manifest / GetToolSpec owner work, or a single concrete tool feature group.

Safety / Behavior

• No concrete tool implementation moved.
• Snapshot behavior still calls the existing wrap_tool_for_snapshot_tracking path through the core-owned product wrapper adapter.
• Tool registry order, collapsed exposure, readonly/enabled filtering, dynamic provider metadata, and GetToolSpec unlock behavior are covered by focused tests.

Validation

• git rebase gcwing/main
• cargo test -p bitfun-agent-tools --test tool_contracts
• cargo test -p bitfun-core product_tool_runtime_assembly --lib
• cargo test -p bitfun-core registry_ --lib
• cargo test -p bitfun-core manifest_ --lib
• cargo test -p bitfun-core get_tool_spec --lib
• cargo test -p bitfun-core dynamic_tool_provider_ --lib
• cargo check -p bitfun-core --features product-full
• cargo check -p bitfun-agent-tools
• cargo check -p bitfun-core
• node scripts/check-core-boundaries.mjs
• rustfmt --edition 2021 --check src/crates/agent-tools/src/framework.rs src/crates/agent-tools/src/lib.rs src/crates/agent-tools/tests/tool_contracts.rs src/crates/core/src/agentic/tools/runtime_assembly.rs
• git diff --check gcwing/main..HEAD