feat(extensions): progress UI + error display during install

[yasinBursali]

What

Show real-time install progress in the Extensions portal with status badges for all lifecycle states.

Why

Users see only a spinner during extension install — no indication of what's happening. If Docker pulls a large image for 5 minutes, there's no progress feedback. If it fails, the error is generic. The frontend also times out at 2 minutes while the backend allows 5 — causing false "failed" messages on slow connections.

How

• Progress polling: During install/enable, polls GET /api/extensions/{service_id}/progress every 3s. Shows phase labels ("Downloading image...", "Starting container...") in the extension card.
• useRef mirror: installProgressRef avoids stale closure bug — the polling interval updates both ref and state, catch block reads from ref.
• Status badges: installing/setting_up show blue badge with spinner. error shows red clickable badge that opens console/log viewer.
• Error detail in toast: When install fails and progress has error data, appends Docker stderr to the toast message.
• Timeout fix: AbortSignal.timeout changed from 120000ms to 300000ms — matches backend _AGENT_TIMEOUT.

Security

• Progress data (phase_label, error) rendered as text content, not dangerouslySetInnerHTML — no XSS risk
• Auth handled by nginx proxy (existing pattern) — no credentials in frontend code
• Error detail truncated to 500 chars at the source (host agent)

Test Coverage

No automated frontend tests (React testing not configured in project). Manual test checklist:

• Install extension → card shows progress phases (Downloading → Starting → enabled)
• Install fails → error badge appears, toast shows Docker stderr detail
• Click error badge → opens console/log viewer
• "Installing" filter shows only installing extensions
• "Setting Up" filter shows only setting-up extensions
• "Error" filter shows only errored extensions
• Summary bar shows Installing and Error counters
• Install takes >2 min → no frontend timeout (was broken at 120s, now 300s)
• setting_up status shows blue badge with "setting up" label + spinner

Three Pillars Impact

• Install Reliability: Improved — users see what's happening, errors are actionable
• Broad Compatibility: No new dependencies, no platform-specific code, pure React/JSX
• Extension Coherence: No impact on dream enable/disable or extension system

Files Changed

File	Changes
extensions/services/dashboard/src/pages/Extensions.jsx	+61/-5 — progress polling, status badges, error display, timeout fix

Platform Impact

• All platforms: Pure frontend change — no platform-specific behavior

Sequence

PR 3 of 3 — Extension Lifecycle States

• PR 1: Fix user extension status (fix(extensions): health-based status for user extensions + restart for stopped services #825) — must merge first
• PR 2: Install progress tracking (feat(extensions): install progress tracking with host agent orchestration #827) — must merge second
• PR 3: Frontend progress UI (this PR)

Note: This PR is stacked on #827 which is stacked on #825. Merge in order: #825 → #827 → this PR.

🤖 Generated with Claude Code

[Lightheartdevs]

Audit: REQUEST CHANGES — CI failing + depends on #827 + merge conflict

Good frontend work — progress polling every 3s, phase labels, useRef mirror to avoid stale closures, error badges with click-to-console. The UX design is well thought out.

Blockers:

1. CI failing: Same Ruff lint + api test failures as #827.

2. Depends on #827: Needs the progress endpoint to exist before this frontend can poll it.

3. Merge conflict: Same Extensions.jsx conflict as #825 and #827. All new UI elements must use theme variables (see mapping in #825 comment).

4. Check for hardcoded colors: Any new badges, spinners, or status text added in this PR should use text-theme-accent / bg-theme-accent/20 / text-theme-text-muted instead of text-indigo-* / bg-zinc-*. The page was just migrated to the liquid metal design system in #829.

Merge order: #825 → #827 → #828

Once #825 is rebased and merged, the whole chain can follow. The backend design in #827 is solid — just needs CI fixes and the rebase.