feat(skills): add schedule, notes, and settings skills

[setkyar]

What

Ship three pi skills so a session can talk to pi-web:

• /skill:pi-web-schedule — create/list/pause/run schedules
• /skill:pi-web-notes — read/append/replace the project scratchpad
• /skill:pi-web-settings — get/set theme, language, auto-title, etc.

They go through pi-web-ctl, which calls the existing HTTP APIs (never SQLite). install.sh / install.ps1 copy the CLI to ~/.pi/agent/bin/pi-web-ctl.

Why

People already say things like “add a schedule at 2am Singapore time” or “write this in the notes.” Those surfaces existed in the UI only. Skills let the agent do the same thing from a session, in the terminal or the web UI.

How

• CLI discovers 127.0.0.1:{port} from pi-web-state.json and sends X-Pi-Token (never ?token=, which 302s past the handler).
• Schedule flags (--daily --hour 2 --timezone sg) compile to cron; aliases like sg resolve to IANA names.
• Notes default to append (POST /api/scratchpad mode=append) so the UI debounce cannot clobber a GET-then-replace.
• Settings use friendly aliases (theme, language, auto-title). Theme/fonts apply live; language reloads open tabs, same as the Settings picker.
• RPC workers and /api/models oneshots no longer inherit pi-web’s checkout cwd. That was loading this repo’s .pi/extensions on top of the installed package and crashing on duplicate pi_web_ask_user_question. Extensions still load.

Tests

• .pi/skills/common/test_pi_web.py — discovery, auth header, cron/tz, notes append, settings aliases
• Go: schedule/scratchpad/settings SSE, scratchpad append
• Frontend: slash-adjacent SSE helpers, scratchpad dirty-aware apply, settings-live locale reload

make test includes pi-web-ctl-test.

Try

pi-web-ctl schedule list
pi-web-ctl notes append --text "hello"
pi-web-ctl settings set theme dark

In a session, type /pi- and pick /skill:pi-web-schedule, /skill:pi-web-notes, or /skill:pi-web-settings.

[setkyar]

Review pass on this branch, plus one follow-up commit (5f0af8c).

Fixed here

• The three SSE helpers (schedules-events.js, scratchpad-events.js, settings-events.js) were byte-identical apart from the event name, and each opened its own EventSource to /events?id=__all__. A session tab already holds the per-session stream, so it went to three connections — two tabs would hit the browser's six-per-host HTTP/1.1 cap and stall fetches and saves. Replaced with web/src/shared/app-events.js: createAppEvents({ event }) multiplexes named events onto one stream per topic and closes it when the last subscriber leaves.
• applyRemote now skips the textarea write when content already matches. Our own debounced save echoes back over SSE, and reassigning value moves the caret for no reason.

Verified, no change needed

• read_token's ~/.config/pi-web/env matches where setup_env writes PI_WEB_TOKEN (install.sh:383-400), and X-Pi-Token is the header internal/auth/auth.go:263 accepts — so the CLI works under the hardened-auth/Tailscale path.
• The worker cwd change is safe: CreateSessionFileWithSettings writes the cwd header before the worker starts (internal/sessions/session.go:844), so workerDir resolves the project dir and never silently falls back to /tmp for a real session.
• _schedule_input covers exactly the nine scheduleInput fields, so a CLI update cannot blank a field the caller did not pass.

Deferred — translations

user-docs/en/{README,install,personal-assistant}.md changed, so AGENTS.md wants scripts/build_userdocs.py re-run. Doing it here means 104 pi calls that rewrite all 13 languages × 7 docs + hero, including files this PR never touched — that turns a skills PR into a docs-rewrite PR. Leaving it for a docs-only regen PR, same as the Windows rollout (#94).

Notes, not blocking

• _url_has_token_query can never fire: every path is hardcoded and quote() encodes =.
• clamp_int silently coerces --hour 99 to 23 rather than erroring.
• schedule update NAME --weekly without --hour resets the time to 09:00 (the flag default).
• sessionHeaderCWD duplicates the unexported sessions.readSessionCWD; worth exporting one if a third caller shows up.
• The scratchpad SSE project match is exact-string, so it no-ops under path aliasing (/tmp vs /private/tmp) — degrades to no live update, which is fine.

make check green on the branch (lint, format, knip, vitest, build, go test ./..., install test, vet), including the new pi-web-ctl-test target.