docs(readme): surface gemini-cli (and copilot, windsurf, 50+ others) in npx skills coverage

npx skills supports 50+ harnesses via the -a flag, including gemini-cli,
github-copilot, windsurf, cline, continue, roo, aider-desk, opencode,
goose, and more — not just the few I'd listed initially. Updating to
reflect that breadth.

- Top-of-file snippet now reads "Codex, Cursor, Copilot, Gemini CLI, or
  any of 50+ Agent Skills hosts" (was: "Codex, Cursor, Copilot, or any
  Agent Skills host" + Gemini listed separately in the table footer).
- Install table: same expansion; Gemini CLI native-extension row relabeled
  to clarify it's the native path (not the only Gemini option).
- npx skills subsection: lists the most common harness flags and links
  to the upstream vercel-labs/skills repo for the full list.
- Gemini CLI native subsection: now leads with "the npx skills path
  above is simpler" and frames the native install as the alternative
  for users with an existing Gemini extensions workflow or who hit
  the v0.9.0 installer bug.

README.md

@@ -19,12 +19,12 @@ This README tracks the current v3 pipeline. The runtime skill spec lives in [SKI
 /plugin marketplace add mvanhorn/last30days-skill
 ```
 
-**Codex, Cursor, Copilot, or any Agent Skills host:**
+**Codex, Cursor, Copilot, Gemini CLI, or any of 50+ [Agent Skills](https://agentskills.io) hosts:**
 ```
 npx skills add mvanhorn/last30days-skill
 ```
 
-More install options (claude.ai web, OpenClaw, Gemini CLI, manual) in the [Install](#install) section below.
+More install options (claude.ai web, OpenClaw, manual) in the [Install](#install) section below.
 
 Zero config. Reddit, HN, Polymarket, and GitHub work immediately. Run it once and the setup wizard unlocks X, YouTube, TikTok, and more in 30 seconds.
 
@@ -167,10 +167,10 @@ Say "eli5 on" after any research run. The synthesis rewrites in plain language.
 | Surface | Install | Updates |
 |---------|---------|---------|
 | **Claude Code** (recommended) | `/plugin marketplace add mvanhorn/last30days-skill` | Auto via marketplace, or `claude plugin update last30days@last30days-skill` |
-| **Codex, Cursor, Copilot, any [Agent Skills](https://agentskills.io) host** | `npx skills add mvanhorn/last30days-skill` | `npx skills update last30days` |
+| **Codex, Cursor, Copilot, Gemini CLI, GitHub Copilot, or any of 50+ [Agent Skills](https://agentskills.io) hosts** | `npx skills add mvanhorn/last30days-skill` | `npx skills update last30days` |
 | **claude.ai** (web) | [Download `last30days.skill`](https://github.com/mvanhorn/last30days-skill/releases/latest/download/last30days.skill) and upload via Settings > Capabilities > Skills > + | Re-download and re-upload |
 | **OpenClaw** | `clawhub install last30days-official` | `clawhub update last30days-official` |
-| **Gemini CLI** | Clone then `gemini extensions install ./last30days-skill` (see below) | Re-pull and reinstall |
+| **Gemini CLI** (native extension) | Clone then `gemini extensions install ./last30days-skill` (see below) | Re-pull and reinstall |
 
 ### Claude Code (recommended)
 
@@ -188,9 +188,9 @@ npx skills add mvanhorn/last30days-skill -a claude-code
 
 The native plugin and the `npx skills` install can coexist; Claude Code dedupes the slash command.
 
-### Codex, Cursor, Copilot, and other Agent Skills hosts
+### Codex, Cursor, Copilot, Gemini CLI, and other Agent Skills hosts
 
-Install via the open [Agent Skills](https://agentskills.io) CLI:
+Install via the open [Agent Skills](https://agentskills.io) CLI — supports 50+ harnesses including `codex`, `cursor`, `github-copilot`, `gemini-cli`, `claude-code`, `windsurf`, `cline`, `continue`, `roo`, `aider-desk`, `opencode`, `goose`, and more (full list on the [vercel-labs/skills repo](https://github.com/vercel-labs/skills)).
 
 ```bash
 npx skills add mvanhorn/last30days-skill
@@ -201,6 +201,7 @@ By default this installs for whichever harness it detects. To target a specific
 ```bash
 npx skills add mvanhorn/last30days-skill -a codex
 npx skills add mvanhorn/last30days-skill -a cursor
+npx skills add mvanhorn/last30days-skill -a gemini-cli
 npx skills add mvanhorn/last30days-skill -a codex -a cursor
 ```
 
@@ -232,7 +233,9 @@ Enable "Code execution and file creation" under Capabilities first — skills wo
 clawhub install last30days-official
 ```
 
-### Gemini CLI
+### Gemini CLI (native extension)
+
+The `npx skills add -a gemini-cli` path above is the simpler route. The native Gemini extension install is kept here for users who prefer it or already have a Gemini extensions workflow.
 
 Gemini CLI v0.9.0 has an upstream installer bug that can fail with `Configuration file not found at /tmp/gemini-extensionXXXXXX/gemini-extension.json` ([upstream issue](https://github.com/google-gemini/gemini-cli/issues/11452)). Workaround: