fix(codemode): unify catalog signatures

[rekram1-node]

Summary

• use one JSDoc-annotated signature representation for inline catalogs and search results
• include schema field descriptions and tags in inline catalog token accounting
• remove the duplicate search signature field so the two surfaces cannot drift
• update CodeMode and OpenCode coverage and documentation

Testing

• bun test in packages/codemode (255 passed)
• bun typecheck in packages/codemode
• bun test test/tool/code-mode.test.ts test/tool/code-mode-integration.test.ts test/tool/registry.test.ts in packages/opencode (68 passed)
• bun typecheck in packages/opencode
• Prettier check for changed files
• git diff --check