feat(mcp): honor external lifecycle timeouts

[limityan]

Summary

• add an ecosystem-neutral external MCP timeout contract for startup, Tool catalog, and execution phases, then map OpenCode, Codex, and Claude Code source semantics without persisting third-party runtime configuration
• enforce explicit phase deadlines in the existing MCP services owner for local and remote transports, preserving timeout error classification and cleaning pending/startup state
• disclose effective overrides in the shared external-source snapshot, Desktop settings, and TUI while keeping omitted values on existing BitFun behavior
• keep runtime-only external MCP Tool-only: Resource/Prompt warmup and unsupported host capabilities are not expanded

Source semantics

Source	Native field	BitFun phases
OpenCode V1	timeout (ms)	startup, Tool catalog, execution
Codex	startup_timeout_sec / legacy startup_timeout_ms	startup and initial Tool catalog
Codex	tool_timeout_sec	execution
Claude Code	per-server timeout (ms)	execution; values below 1000 ms retain Claude Code's ignored-value behavior

Timeout values that cannot cross Rust/JSON/JavaScript surfaces losslessly fail closed at the adapter, product-contract, and native-runtime boundaries.

Architecture and non-goals

• product domains own stable disclosed facts; ecosystem adapters own native parsing; Assembly performs the single mapping into native MCP config; services-integrations owns process/transport deadline behavior; GUI/TUI only consume the shared projection
• no Plugin Host Runtime, LSP, SSE/OAuth expansion, Agent-scoped MCP, marketplace/cache support, OpenCode V2 phased schema, retry, or replay is added
• a deadline stops BitFun waiting; it does not claim the server-side operation was cancelled and it is not reset by progress notifications
• the existing manager-wide external lifecycle lock can still let cross-server rapid re-enable contention consume the outer startup guard; correcting that requires a separate per-server fencing/atomic-publication refactor rather than a timeout workaround

Validation

• cargo test -p bitfun-product-domains --features external-sources --test external_source_contracts (47 passed)
• OpenCode/Codex/Claude Code MCP adapter suites (10 / 18 / 12 passed)
• services MCP lib/contracts/streamable HTTP suites (18 / 43 / 2 passed)
• cargo test -p bitfun-core --features product-full external_mcp (9 passed)
• focused Web external-source API/settings suites (77 passed)
• cargo check -p bitfun-core --features product-full
• cargo check -p bitfun-cli
• Web type-check and lint
• i18n contract (37 passed) and audit (0 warnings)
• Core boundary and repository hygiene checks