Fold BAML Bridge into Workspace

[darinkishore]

Summary

Vendors the BAML bridge infrastructure into the workspace.

Note this PR also adds an AGENTS.md file that references beads for rn, can/should remove before merging .

Crates Added

Crate	Purpose
baml-bridge	Public API: BamlType trait, render_schema, parse_llm_output
baml-bridge-derive	#[derive(BamlType)] proc-macro
baml-types	Core type IR, constraints, BamlValue representation
internal-baml-jinja	Output format schema renderer
jsonish	Fuzzy JSON parser for LLM outputs
internal-baml-diagnostics	Error handling
bstd	Standard library utilities

Key Functionality

• Schema Rendering: render_schema::<T>() generates JSON schema instructions for prompts
• Fuzzy Parsing: parse_llm_output::<T>() handles malformed JSON (missing quotes, trailing commas, markdown fences)
• Derive Macro: #[derive(BamlType)] auto-generates type IR and conversion traits
• Constraint Validation: Built-in @check and @assert constraint support

Notes

• Trimmed to exclude full compiler/runtime - only schema rendering and parsing retained
• 16 trybuild UI tests for derive macro error messages