test(app-server): fix context reload negotiation coverage

[kev1n77]

Summary

Fix the handshake test that expected session/reloadContext without injecting its provider.

• Use the existing runtime fixture with context reload support and verify the advertised RPC reaches its provider.
• Add coverage ensuring the method is omitted when no provider is injected.
• Update stale test DTO initializers and remove calls to the retired local-command RPC.
• Document the focused integration test command.

Fixes #2694

Type and Areas

Type: Test / bug fix

Areas: Rust app-server integration tests and verification documentation.

Motivation / Impact

The integration test target failed to compile because its fixtures used outdated interfaces. After resolving those errors, the handshake test failed with missing advertised method session/reloadContext.

The test now supplies the provider required by its capability expectations and covers both provider-present and provider-absent cases.

No direct user-facing change.

Verification

• cargo test --locked --offline -p openbitfun-app-server --test agent_kernel — 17 passed, 0 failed.
• pnpm run fmt:rs — passed.
• git diff --check — passed.

Verification used local in-memory client/server transport. Remote workspace, remote control, Peer Device Mode, and Detached Dispatch were not exercised.

Reviewer Notes

This fixes the test failure reported in #2694. The failure was reproduced without introducing the connection-timeout configuration change, so this fix does not establish the issue's proposed causal relationship.

Production behavior, protocol contracts, and persisted data formats are unchanged.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.