chore(agent-skills): Update README & improve discoverability

[annguy3n]

Description

• Skills Folder Migration: Relocated the skills/ directory (containing the bigtable skill)
  from agents/skills/ to the root directory for easier access.
• Path & Registry Updates:
  • Updated .claude-plugin/plugin.json, .codex-plugin/plugin.json, and
    .cursor-plugin/plugin.json to point to the new root-level skills/ path.
  • Modified .claude-plugin/marketplace.json to use url as the source type for the
    Bigtable plugin.
• Documentation: Updated the root README.md to highlight support for Bigtable Skills.

Testing

Gemini CLI

[an:~]$ gemini extensions install https://github.com/annguy3n/cloud-bigtable-ecosystem
Installing extension "bigtable".
This extension will run the following MCP servers:
  * bigtable (remote): 
This extension will append info to your gemini.md context using SKILL.md
The extension you are about to install may have been created by a third-party developer and sourced from a public repository. Google does not vet, endorse, or guarantee the functionality or security of extensions. Please carefully inspect any extension and its source code before installing to understand the permissions it requires and the actions it may perform.
Do you want to continue? [Y/n]: Y
✔ Project ID
ID of the Google Cloud project … cloud-bigtable-spacewalk
✔ Instance
ID of the Bigtable instance … annenguyen-spacewalk
✔ Cluster
ID of the Bigtable cluster (optional) … 
Extension "bigtable" has missing settings: Cluster. Please run "gemini extensions config bigtable [setting-name]" to configure them.
Extension "bigtable" has missing settings: Cluster. Please run "gemini extensions config bigtable [setting-name]" to configure them.Keychain initialization encountered an error: Cannot find module '../build/Release/keytar.node'
Require stack:
- /usr/local/Cellar/gemini-cli/0.38.2/libexec/lib/node_modules/@google/gemini-cli/node_modules/keytar/lib/keytar.js
Using FileKeychain fallback for secure storage.
Extension "bigtable" installed successfully and enabled.

Claude

Codex

Cursor

[gemini-code-assist]

Code Review

This pull request restructures the project by moving the 'skills' directory from 'agents/skills/' to the root level and updating the corresponding paths in the plugin configuration files and .gitignore. Additionally, the source type in the marketplace configuration was changed from 'git' to 'url'. Feedback was provided regarding the source type change in marketplace.json, as using 'url' with a .git repository link may cause compatibility issues with discovery tools.