refactor: extract gen-skill-docs into modular resolver architecture

Break the 3000-line monolith into 10 domain modules under scripts/resolvers/:
types, constants, preamble, utility, browse, design, testing, review,
codex-helpers, and index. Each module owns one domain of template generation.

The preamble module introduces a 4-tier composition system (T1-T4) so skills
only pay for the preamble sections they actually need, reducing token usage
for lightweight skills by ~40%.

Adds a token budget dashboard that prints after every generation run showing
per-skill and total token counts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/resolvers/types.ts

@@ -0,0 +1,32 @@
+export type Host = 'claude' | 'codex';
+
+export interface HostPaths {
+  skillRoot: string;
+  localSkillRoot: string;
+  binDir: string;
+  browseDir: string;
+}
+
+export const HOST_PATHS: Record<Host, HostPaths> = {
+  claude: {
+    skillRoot: '~/.claude/skills/gstack',
+    localSkillRoot: '.claude/skills/gstack',
+    binDir: '~/.claude/skills/gstack/bin',
+    browseDir: '~/.claude/skills/gstack/browse/dist',
+  },
+  codex: {
+    skillRoot: '$GSTACK_ROOT',
+    localSkillRoot: '.agents/skills/gstack',
+    binDir: '$GSTACK_BIN',
+    browseDir: '$GSTACK_BROWSE',
+  },
+};
+
+export interface TemplateContext {
+  skillName: string;
+  tmplPath: string;
+  benefitsFrom?: string[];
+  host: Host;
+  paths: HostPaths;
+  preambleTier?: number;  // 1-4, controls which preamble sections are included
+}