fix: embed host compaction baml

[neithanmo]

Summary

Embeds host compaction BAML into agentium, fixing release/runtime boot failures when baml_src/host is not present on disk.

Issue: host compaction previously loaded BAML from loose files (BAML_HOST_SCHEMA_DIR, /opt/agentium, or repo fallback). Release tar users do not get those files, and binaries can resolve to build-machine paths. This made users download/copy extra BAML sidecars or required us to add BAML files to release artifacts.

This PR opts for embedded BAML via include_str! + in-memory BAML runtime loading. Result: agentium binary is self-contained for host compaction, release tar layout stays binaries-only, and users do not need extra BAML files. BAML_HOST_SCHEMA_DIR still works as override for dev/operator custom BAML.

What's in the diff

• crates/baml-rt-quickjs/src/baml_execution.rs

  • Adds BamlExecutor::load_il_from_content, using BamlRuntime::from_file_content.
  • Shares default executor setup through from_runtime.

• crates/baml-rt-quickjs/src/baml/schema_invoke.rs

  • Adds BamlRuntimeManager::load_schema_from_files.
  • Extracts shared schema wiring into finish_schema_load.
  • In-memory path skips disk-only tool/schema manifest sidecars and explicitly clears those manifest slots.

• crates/baml-rt-a2a/src/host_compaction/mod.rs

  • Replaces raw schema dir config with HostCompactionSource::{Embedded, Dir}.
  • Boots embedded source through load_schema_from_files.
  • Keeps directory source for override compatibility.

• crates/baml-rt-a2a/src/lib.rs

  • Re-exports HostCompactionSource.

• crates/baml-agent-runner/src/host_compaction.rs

  • Embeds baml_src/host/clients.baml and baml_src/host/context_compaction.baml.
  • Defaults to embedded BAML.
  • Keeps BAML_HOST_SCHEMA_DIR override.
  • Removes /opt/agentium probe and repo fallback.

• Dockerfile

  • Removes COPY baml_src/host /opt/agentium/baml_src/host.
  • Removes ENV BAML_HOST_SCHEMA_DIR=/opt/agentium.

• Tests

  • Adds in-memory loader tests in crates/baml-rt-quickjs/tests/load_schema_from_files_test.rs.
  • Updates host compaction tests to boot embedded source.
  • Keeps directory override boot coverage.

Test plan

• cargo clippy --all-targets --all-features -- -D warnings clean
• cargo fmt --check clean (cargo fmt --all run)
• cargo test / cargo nextest run pass for the affected crates
  • cargo test -p baml-rt-quickjs load_schema_from_files --no-default-features
  • cargo test -p baml-rt-a2a host_compaction --no-default-features

Checklist

• Commit subjects and the PR title follow Conventional Commits
• Documentation updated where behavior changed
• No secrets, credentials, or partner-specific names in the diff