Add network-dependent smoke tests for remote URL KB sources

[rucka]

Context

Follow-up from PR #133 (Story #92) code review. Remote URL smoke tests were deferred because they require network access and are not suitable for offline CI environments.

Problem

Current smoke tests (scripts/smoke-tests/scenarios/source-resolution.sh) only cover local sources (directories, offline mode). Remote URL scenarios are not tested end-to-end:

• Install from remote HTTPS URL
• Update from remote HTTPS URL
• Network failure handling (timeout, connection refused)
• Download retry with exponential backoff
• Progress indicator during download

Proposed Solution

Create new smoke test scenario for network-dependent tests:

File: scripts/smoke-tests/scenarios/remote-source-resolution.sh

Tag: OFFLINE_SAFE=false (filtered out by --offline-only flag)

Test scenarios:

1. Install from remote HTTPS URL (GitHub release artifact)
2. Update from remote HTTPS URL
3. Download progress indicator verification (TTY output check)
4. Error: Invalid URL (malformed)
5. Error: 404 Not Found
6. Error: Network timeout (simulated with bad URL)

Mock setup:

• Use real GitHub release URL for testing (predictable, stable)
• Alternative: Set up local HTTP server with test fixtures

Acceptance Criteria

• remote-source-resolution.sh created with OFFLINE_SAFE=false tag
• Test 1: Install from HTTPS URL succeeds
• Test 2: Update from HTTPS URL succeeds
• Test 3: Progress indicator shows during download
• Test 4: Malformed URL rejected with clear error
• Test 5: 404 error handled gracefully
• Test 6: Network timeout triggers retry logic
• Tests skipped when --offline-only flag used
• Tests run in CI environment with network access
• Update run-all.sh to include new scenario (but exclude with --offline-only)

Technical Notes

Retry verification:

• Simulate transient failure (connection refused)
• Verify retry attempts with exponential backoff (1s, 2s, 4s)
• Verify max 3 retries before giving up

Progress verification:

• Capture stdout during download
• Verify progress indicator format: [N/M] registry-name
• Verify operation summary at completion

Priority

Low - Unit tests already cover retry logic and error handling. Smoke tests provide additional E2E confidence but are not critical for correctness.

Related

• PR [#92] feat: flexible KB source resolution #133 (story Flexible KB Source Resolution #92 implementation)
• Epic Simple KB Distribution & Installation #65 (Enhanced CLI Packaging & Distribution)
• Existing: scripts/smoke-tests/scenarios/source-resolution.sh (local-only tests)