fix(ci): make post-merge smoke and Rust tests portable

[jmagar]

Summary

• install the sqlite3 CLI in the shared Rust setup action so cross-process WAL and stress-harness tests have their declared runtime dependency
• build the reusable Linux smoke binary on pinned Ubuntu 24.04
• run the MCP smoke consumer on the same pinned Ubuntu runtime, preventing OpenSSL ABI mismatches between TOOTIE-built artifacts and GitHub-hosted execution
• add workflow-shape regression tests for both portability contracts

Root causes observed after PR #491 merged

• TOML formatting failed on a temporary DOOKIE runner whose mise subprocess inherited an unusable kache wrapper; that runner has been removed
• the full test job failed because the TOOTIE Rust runner lacked sqlite3; this caused both the WAL test and the stress harness to fail before the loopback-Qdrant assertion
• MCP smoke downloaded a TOOTIE-built binary requiring OpenSSL 3.2/3.3 and executed it on Ubuntu 24.04, which provides an older OpenSSL ABI

Verification

• targeted workflow contracts: 24 passed
• loopback-Qdrant stress regression: passed
• cross-process SQLite WAL regression: passed
• full just precommit: 4,899/4,899 tests passed, 6 skipped
• Clippy, cargo check, rustfmt, repository policies, and actionlint passed