Rename @mariozechner/pi-coding-agent to @earendil-works/pi-coding-agent

Pi moved to its new home at earendil-works on 2026-05-07
(https://pi.dev/news/2026/5/7/pi-has-a-new-home).

The old @mariozechner/pi-coding-agent npm package is deprecated with
the explicit message 'please use @earendil-works/pi-coding-agent
instead going forward', and the version stream has moved on (old
top-out 0.73.1; new currently 0.74.0). Anyone npm-installing the old
name today gets a deprecation warning + a stale binary, so this is
a non-optional migration before the next tagged release.

Sweep:
- Dockerfile (production single-Dockerfile path) and Dockerfile.variant
  (split-base path on main): npm install -g target updated.
- README, AGENTS, HUB_TEMPLATE: github.com/mariozechner/pi-coding-agent
  URL refs (which now 404) -> github.com/earendil-works/pi.
- DOCKER_HUB.md regenerated (5529 bytes, ~78% headroom).
- CHANGELOG Unreleased: rename entry added with migration context.

Brew install references (`brew install pi-coding-agent`) left as-is:
formula still works at 0.73.1 and a homebrew tap update is tracked
upstream at earendil-works/pi#2755.

Historical CHANGELOG entries: only github URL refs updated (the
package name was never spelled out in those entries; we're correcting
dead hyperlinks, not rewriting feature descriptions).

CHANGELOG.md

@@ -17,6 +17,7 @@ Docs-only updates that don't trigger a new image build (Docker Hub description w
 
 Image changes (will ship in the next tagged release):
 
+- **Rename:** `npm install -g @mariozechner/pi-coding-agent` -> `npm install -g @earendil-works/pi-coding-agent` in the `INSTALL_PI=true` build path. Pi moved to its new home at earendil-works on 2026-05-07 (https://pi.dev/news/2026/5/7/pi-has-a-new-home); the old `@mariozechner/*` packages are deprecated on npm with the explicit message 'please use @earendil-works/pi-coding-agent instead going forward', and the version stream has moved on (old top-out 0.73.1; new currently 0.74.0). Anyone npm-installing the old name today gets a deprecation warning + a stale binary. Affects both `Dockerfile` (production single-Dockerfile path) and `Dockerfile.variant` (split-base path on `feat/split-build`/main). README, AGENTS, and `HUB_TEMPLATE` URL refs updated from `github.com/mariozechner/pi-coding-agent` (which now 404s) to `github.com/earendil-works/pi`. Brew install references (`brew install pi-coding-agent`) left as-is: formula still works at 0.73.1 and a homebrew tap update is tracked upstream at earendil-works/pi#2755.
 - **Fix:** `pi install npm:<pkg>` (and any `npm install -g`) by the `developer` user no longer EACCES against the system npm prefix. `NPM_CONFIG_PREFIX` is now `/home/developer/.pi/npm-global` and the prefix's `bin/` is prepended to `PATH`. The directory lives on the `devbox-pi-config` named volume, so user-installed pi packages (themes, skills, extensions) survive container recreation and image rebuilds. Build-time `npm install -g` calls (opencode, pi, oh-my-opencode-slim) are unaffected because the new ENVs are declared after those steps in the Dockerfile, so the baked binaries still install to `/usr` and are not shadowed by the volume mount.
 
 Build pipeline (branch `feat/split-build`, not yet merged):
@@ -33,7 +34,7 @@ Docs-only (the DOCKER_HUB.md change can be patched live to Hub without a CI rebu
 
 **Optional pi as second harness.**
 
-- **Feature:** New `INSTALL_PI=true` build arg installs [pi](https://github.com/mariozechner/pi-coding-agent) as an alternative or complementary harness alongside opencode. Both harnesses share the same mempalace install and palace path — wing/diary entries are mutually visible. Adds ~150 MB to the image. Pi version pinned by `PI_VERSION` (default: latest at build time); `pi update` inside the container does not persist across `--rm` containers — image rebuild is the upgrade path, same contract as `OPENCODE_VERSION`.
+- **Feature:** New `INSTALL_PI=true` build arg installs [pi](https://github.com/earendil-works/pi) as an alternative or complementary harness alongside opencode. Both harnesses share the same mempalace install and palace path — wing/diary entries are mutually visible. Adds ~150 MB to the image. Pi version pinned by `PI_VERSION` (default: latest at build time); `pi update` inside the container does not persist across `--rm` containers — image rebuild is the upgrade path, same contract as `OPENCODE_VERSION`.
 - **Feature:** New `INSTALL_OPENCODE=false` build arg builds an image without opencode (e.g. for pi-only use). Default remains `true`. Existing builds and tags are unaffected.
 - **Feature:** New `devbox-pi-config` named volume mounted at `~/.pi/` persists pi user state (settings.json, `/ext`-disabled extensions) across container recreate. Mirrors the `devbox-opencode-config` pattern from v1.14.33.
 - **Feature:** Container clones [pi-toolkit](https://gitea.jordbo.se/joakimp/pi-toolkit) (keybindings, env loader, settings template) and [pi-extensions](https://gitea.jordbo.se/joakimp/pi-extensions) (6 extensions including ext-toggle, todo, ssh-controlmaster, notify, git-checkpoint, confirm-destructive) into `/opt/` at build time. New `PI_TOOLKIT_REF` and `PI_EXTENSIONS_REF` build args (default `main`) pin git refs. The mempalace pi-bridge `mempalace.ts` is symlinked from the existing `/opt/mempalace-toolkit/` clone.