feat(native): discover models natively behind the compiler engine switch (#995)

* feat(native): discover SQL model files natively behind the compiler engine switch

Add the sqlbuild-discovery crate with a parallel directory walk that keeps
Python's glob and sort semantics, and native reading and parsing of SQL model
files with Python's exact discovery messages, locations and ordering.
With SQLBUILD_COMPILER_ENGINE=native the discovery stage takes its model
files from the native walk; every other collection still runs in Python.
Native discovery skips the Python discovery fact cache.

* fix(native): defer model discovery to Python when it cannot match exactly

Run the Python path when the running Python's Unicode database differs from
the native character table or the project root is not UTF-8, and share the
native models walk with the pass's directory snapshot.

* test(compiler): pass every frontier stage through the perturbation hooks

Author: kvlonge

Cargo.lock

@@ -3,6 +3,7 @@ members = [
     "crates/sqlbuild-core",
     "crates/sqlbuild-sqltext",
     "crates/sqlbuild-config",
+    "crates/sqlbuild-discovery",
     "crates/sqlbuild-analysis",
     "crates/sqlbuild-rules",
     "crates/sqlbuild-python",
@@ -17,6 +18,7 @@ order = [
     "sqlbuild-core",
     "sqlbuild-sqltext",
     "sqlbuild-config",
+    "sqlbuild-discovery",
     "sqlbuild-analysis",
     "sqlbuild-rules",
     "sqlbuild-python",
@@ -64,6 +66,7 @@ sha2 = "0.10"
 sqlbuild-analysis = { path = "crates/sqlbuild-analysis" }
 sqlbuild-config = { path = "crates/sqlbuild-config" }
 sqlbuild-core = { path = "crates/sqlbuild-core" }
+sqlbuild-discovery = { path = "crates/sqlbuild-discovery" }
 sqlbuild-rules = { path = "crates/sqlbuild-rules" }
 sqlbuild-sqltext = { path = "crates/sqlbuild-sqltext" }
 stacker = "0.1"

Cargo.toml

@@ -9,6 +9,7 @@ that can be tested and benchmarked with `cargo test` alone.
 | `sqlbuild-core` | Constants shared by several crates, the panic boundary that turns an unwinding native failure into a named compiler error, passive identity, diagnostic and SQL value types, text positions, and a JSON emitter whose output matches Python's `json.dumps` and `orjson` byte for byte. |
 | `sqlbuild-sqltext` | Lexical SQL text without polyglot: comment, quote and parenthesis scanning, the rules quote policy, model header tokenization and matching, static variable substitution and static reference extraction. |
 | `sqlbuild-config` | Configuration file reading without Python: `tomllib`-compatible TOML, PyYAML `safe_load`-compatible YAML 1.1, and typed project and local config readers for the fields discovery needs. Any error means "defer to Python", which re-parses for exact messages. |
+| `sqlbuild-discovery` | Native project discovery: the shared directory walk with Python's glob and sort semantics, file reading with Python's newline handling, and parsing of authored files with Python's exact discovery messages. Results are plain data the Python discovery facade materialises; anything it cannot reproduce exactly defers to Python. |
 | `sqlbuild-analysis` | SQL analysis over polyglot: SQL tokens, query analysis, the binding catalog, semantic validation and usage, column references, and SQL-test extraction, planning and rendering. |
 | `sqlbuild-rules` | Built-in rules and the rules engine, the custom-rule host, SQL lint, quality checks and formatting, rules configuration and the request models. It also owns the build identity script. |
 | `sqlbuild-python` | The only PyO3 crate: the `_native` module, its Python classes and functions, conversions from Python objects, and the process allocator. |
@@ -19,7 +20,8 @@ Dependencies point one way, from the top of this graph to the bottom:
 
 ```text
 sqlbuild-python
-  -> sqlbuild-rules -> sqlbuild-analysis -> sqlbuild-config -> sqlbuild-sqltext -> sqlbuild-core
+  -> sqlbuild-rules -> sqlbuild-analysis -> sqlbuild-discovery -> sqlbuild-config
+  -> sqlbuild-sqltext -> sqlbuild-core
 ```
 
 `sqlbuild-config` does not depend on the crates below it today; its place in the order only