feat(compiler): implement compile_query for v0.2.0

[ClodoCapeo]

Context

queryme.compile_query() is a stub since v0.1.0 (raises NotImplementedError). v0.2.0 implements it so consuming services (ZabTruth first) can ship POST /api/v1/_query.

Reference : ADR 001 §Phase 2 at D:/Document/ZabLaboratory/docs/adr/001-blueprint-db-access.md (étage 1, hors git).

Approach

Compiler is self-contained — it builds a synthetic MetaData from the SchemaDescriptor rather than asking the service for its own metadata. Services just execute the resulting Select against their async engine and serialise rows. Decision rationale : QueryMe stays a pure library, no service-side wiring contract beyond the Select itself.

Acceptance criteria

• compile_query(descriptor, schema) -> sqlalchemy.Select returns a working SELECT statement.
• Synthetic MetaData built from SchemaDescriptor ; closed ColumnType mapped to SQLAlchemy types (String, Text, Integer, Float, Boolean, Uuid, DateTime, Date, JSON).
• Supports : single FROM, multiple INNER JOINs, AND-joined WHERE, multiple ORDER BY, LIMIT, OFFSET.
• All 9 WHERE operators implemented : =, !=, >, <, >=, <=, IN, LIKE, IS NULL.
• Re-validates input via validate_against_schema ; on issues, raises CompilationError carrying the structured issues (no silent failure, no half-built statement).
• Resolves both unqualified (col) and qualified (table.col) references in WHERE / ORDER / JOIN.
• Tests cover : every operator, join (single + chained), order, limit/offset, qualified refs, error path with bad descriptor.
• CI green : ruff clean, mypy strict clean, full pytest suite passes.

Out of scope

• Mutation (INSERT/UPDATE/DELETE) — Phase 2.x per ADR 001.
• Ambiguous unqualified column references (same name on multiple joined tables) — currently first-match, will tighten in v0.3 with a validator warning.
• Type coercion of WHERE values vs column types — delegated to SQLAlchemy / database layer.

Definition of done

PR opened against main, CI green, maintainer reviews and squash-merges. Branch deletion + tag v0.2.0 are maintainer calls.