docs(readme): recommend Claude Code plugin, add npx skills install for Codex/Cursor/Copilot

The skill is now installable across every major agent harness after the
SKILL.md path-resolver work landed in PR #400 + #404. README didn't yet
reflect that — the install table only listed Claude Code, OpenClaw, and
Gemini CLI, and the top-of-file install snippets featured Hermes (an
internal dev workflow, not a public install method).

Restructured the install section:

- Top-of-file snippets: just Claude Code (recommended, auto-updates) and
  the universal `npx skills add` one-liner. Dropped Hermes from the
  prominent spot (internal-only); pointed everything else to the Install
  section below.
- Install table: added a third column for update commands, since every
  harness now has a distinct update path worth surfacing. Added the
  `npx skills` row covering Codex/Cursor/Copilot/any Agent Skills host.
- Claude Code subsection: explains why it's recommended (marketplace
  handles versioned cache + auto-refresh) and notes that the agent-skills
  install also works on Claude Code if preferred (`-a claude-code`).
- New "Codex, Cursor, Copilot, and other Agent Skills hosts" subsection:
  shows the default install, per-harness `-a` targeting, and the update
  commands (`npx skills update last30days` for one skill, bare
  `npx skills update` for all).
- Manual (developer) subsection: switched from a clone-into-skills-dir
  recipe to a clone + symlink recipe. Symlink keeps the install in sync
  with the working tree as you edit, no re-copy on each change.

No code changes. No version bump (docs-only).

README.md

@@ -14,21 +14,17 @@
 
 This README tracks the current v3 pipeline. The runtime skill spec lives in [SKILL.md](SKILL.md), which is the source of truth for the latest command and setup behavior.
 
-Claude Code:
+**Claude Code (recommended — auto-updates via marketplace):**
 ```
 /plugin marketplace add mvanhorn/last30days-skill
 ```
 
-OpenClaw:
+**Codex, Cursor, Copilot, or any Agent Skills host:**
 ```
-clawhub install last30days-official
+npx skills add mvanhorn/last30days-skill
 ```
 
-Hermes:
+More install options (claude.ai web, OpenClaw, Gemini CLI, manual) in the [Install](#install) section below.
-```
-# The skill auto-deploys when you run sync.sh
-# Or manually copy to ~/.hermes/skills/research/last30days/
-```
 
 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.
 
@@ -168,12 +164,59 @@ Say "eli5 on" after any research run. The synthesis rewrites in plain language.
 
 ## Install
 
-| Surface | Install |
+| Surface | Install | Updates |
-|---------|---------|
+|---------|---------|---------|
-| **claude.ai** (web) | [Download `last30days.skill`](https://github.com/mvanhorn/last30days-skill/releases/latest/download/last30days.skill) and upload via Settings > Capabilities > Skills > + |
+| **Claude Code** (recommended) | `/plugin marketplace add mvanhorn/last30days-skill` | Auto via marketplace, or `claude plugin update last30days@last30days-skill` |
-| **Claude Code** | `/plugin marketplace add mvanhorn/last30days-skill` |
+| **Codex, Cursor, Copilot, any [Agent Skills](https://agentskills.io) host** | `npx skills add mvanhorn/last30days-skill` | `npx skills update last30days` |
-| **OpenClaw** | `clawhub install last30days-official` |
+| **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 |
-| **Gemini CLI** | Clone then `gemini extensions install ./last30days-skill` (see below) |
+| **OpenClaw** | `clawhub install last30days-official` | `clawhub update last30days-official` |
+| **Gemini CLI** | Clone then `gemini extensions install ./last30days-skill` (see below) | Re-pull and reinstall |
+
+### Claude Code (recommended)
+
+```
+/plugin marketplace add mvanhorn/last30days-skill
+```
+
+Recommended because the Claude Code marketplace handles updates for you — the plugin cache is versioned and auto-refreshes when a new release publishes. Run `claude plugin update last30days@last30days-skill` to force a check.
+
+If you'd rather use the agent-skills install path on Claude Code, that's also supported:
+
+```
+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
+
+Install via the open [Agent Skills](https://agentskills.io) CLI:
+
+```bash
+npx skills add mvanhorn/last30days-skill
+```
+
+By default this installs for whichever harness it detects. To target a specific one (or multiple):
+
+```bash
+npx skills add mvanhorn/last30days-skill -a codex
+npx skills add mvanhorn/last30days-skill -a cursor
+npx skills add mvanhorn/last30days-skill -a codex -a cursor
+```
+
+Update later with:
+
+```bash
+npx skills update last30days
+```
+
+Or update everything you've installed via `npx skills`:
+
+```bash
+npx skills update
+```
+
+List and remove with `npx skills list` and `npx skills remove last30days`.
 
 ### claude.ai (web)
 
@@ -181,15 +224,7 @@ Say "eli5 on" after any research run. The synthesis rewrites in plain language.
 2. Go to [claude.ai Settings > Capabilities > Skills](https://claude.ai/settings/capabilities)
 3. Click the `+` button in the Skills panel and drop the file in
 
-Enable "Code execution and file creation" under Capabilities first - skills won't run without it.
+Enable "Code execution and file creation" under Capabilities first — skills won't run without it.
-
-### Claude Code
-
-```
-/plugin marketplace add mvanhorn/last30days-skill
-```
-
-Update later with `claude plugin update last30days@last30days-skill`.
 
 ### OpenClaw
 
@@ -209,10 +244,11 @@ gemini extensions install ./last30days-skill
 ### Manual (developer)
 
 ```bash
-git clone https://github.com/mvanhorn/last30days-skill.git ~/.claude/skills/last30days
+git clone https://github.com/mvanhorn/last30days-skill.git
+ln -s "$(pwd)/last30days-skill/skills/last30days" ~/.claude/skills/last30days
 ```
 
-Or build the claude.ai `.skill` file from source: `bash skills/last30days/scripts/build-skill.sh` produces `dist/last30days.skill`.
+The symlink keeps the install in sync with your working tree as you edit — no re-copy needed. For `claude.ai`, build the `.skill` file from source: `bash skills/last30days/scripts/build-skill.sh` produces `dist/last30days.skill`.
 
 Reddit (with comments), Hacker News, Polymarket, and GitHub work immediately. Zero configuration. Run `/last30days` once and the setup wizard unlocks more sources in 30 seconds.