Add account-pane: self-service password change, account deletion, data export

[melvincarvalho]

Summary

A focused pane for JSS account self-service. Drives the IDP endpoints that already (or will) exist server-side, so users don't need curl/CLI to manage their own account.

Distinct from the broader #1 (Settings pane) — this one is narrowly scoped to account lifecycle managed by the IDP, not pod content / preferences / system settings.

Sections

Change password ✓ (server ready as of JSS 0.0.165)

• `PUT /idp/credentials` with `{currentPassword, newPassword}`
• Form: current password, new password, confirm new password
• On success: confirmation toast, optional re-login prompt
• Tracks: Add HTTP endpoint for end users to change their own password JavaScriptSolidServer/JavaScriptSolidServer#351 (closed/shipped)

Delete account (server-side TBD)

• Tracks: Add HTTP endpoint + UI for end users to delete their own account JavaScriptSolidServer/JavaScriptSolidServer#352 (open)
• UI: form + danger-confirmation pattern (type pod name to confirm)
• Blocked on server endpoint

Export pod data (server-side TBD)

• Tracks: Add self-service data export — download all my pod data JavaScriptSolidServer/JavaScriptSolidServer#353 (open)
• UI: button → triggers download (JSON-LD bundle, tarball, etc.)
• Blocked on server endpoint

Pod portability — restore / migrate (server-side TBD)

• Tracks: Pod portability: restore from export, rename, cross-origin migration JavaScriptSolidServer/JavaScriptSolidServer#354 (open)
• UI: import + cross-origin-migration flows
• Likely a v2 — the trio above ship first

Implementation notes

• Pane file: `panes/account-pane.js`
• `canHandle`: probably show on user's profile resource (`#me` / WebID owner) when caller's WebID matches the pod owner
• Auth: `window.xlogin.authFetch` (already used by sharing-pane)
• xlogin guard: same pattern as sharing-pane: login prompt for anonymous viewers (#8) #10 — only render when authenticated; anonymous shows "Log in to manage your account"

Out of scope

• Profile editing (display name / avatar / bio) — belongs in Settings pane — pod configuration and system settings #1
• Theme / notification preferences — belongs in Settings pane — pod configuration and system settings #1
• WebAuthn rotation — separate concern (feat: Add passkey (WebAuthn) authentication support JavaScriptSolidServer/JavaScriptSolidServer#78)
• Recovery / forgot-password (no current password) — separate concern, server-side too

Acceptance

Phase 1 — change-password section only (the only one with a live endpoint):

• `panes/account-pane.js` exists, registered in `mashlib.js`
• `canHandle` shows on owner's profile only
• Form: current / new / confirm-new, calls `PUT /idp/credentials`
• Happy path: 200 → success toast
• 401 (wrong current password): inline error, fields preserved
• Anonymous viewer: login prompt empty-state (sharing-pane: login prompt for anonymous viewers (#8) #10 pattern)

Phase 2 onwards — added as server endpoints land for #352, #353, #354.