refactor: initial build system refactor for unified skills

- Renamed postgres-best-practices-build to skills-build
- Moved postgres files to src/postgres/ subdirectory
- Updated BUILD_DIR paths in postgres/config.ts
- Updated type imports to reference ../types.js
- Created IMPLEMENTATION_GUIDE.md with detailed step-by-step tasks

This is the foundation for a unified build system that will support
both postgres-best-practices (rule-based) and supabase (reference-based) skills.

Next steps documented in IMPLEMENTATION_GUIDE.md (Tasks 1-6).

packages/skills-build/src/postgres/build.ts

@@ -2,7 +2,7 @@ import { existsSync, readdirSync, readFileSync, writeFileSync } from "node:fs";
 import { basename, join } from "node:path";
 import { AGENTS_OUTPUT, METADATA_FILE, RULES_DIR } from "./config.js";
 import { parseRuleFile } from "./parser.js";
-import type { Metadata, Rule, Section } from "./types.js";
+import type { Metadata, Rule, Section } from "../types.js";
 import { validateRuleFile } from "./validate.js";
 
 /**

packages/skills-build/src/postgres/config.ts

@@ -4,8 +4,8 @@ import { fileURLToPath } from "node:url";
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);
 
-// Build package directory
-export const BUILD_DIR = join(__dirname, "..");
+// Build package directory (now we're in src/postgres/, so go up two levels)
+export const BUILD_DIR = join(__dirname, "../..");
 
 // Skill directory (relative to build package)
 export const SKILL_DIR = join(

packages/skills-build/src/postgres/parser.ts

@@ -1,7 +1,7 @@
 import { readFileSync } from "node:fs";
 import { basename } from "node:path";
 import { IMPACT_LEVELS } from "./config.js";
-import type { CodeExample, ImpactLevel, ParseResult, Rule } from "./types.js";
+import type { CodeExample, ImpactLevel, ParseResult, Rule } from "../types.js";
 
 /**
  * Parse YAML-style frontmatter from markdown content

packages/skills-build/src/postgres/validate.ts

@@ -3,7 +3,7 @@ import { basename, join } from "node:path";
 import { generateSectionMap, parseSections } from "./build.js";
 import { IMPACT_LEVELS, RULES_DIR } from "./config.js";
 import { parseRuleFile } from "./parser.js";
-import type { ValidationResult } from "./types.js";
+import type { ValidationResult } from "../types.js";
 
 /**
  * Check if an example label indicates a "bad" pattern