feat(cli): add progress feedback to upgrade command

[szzhoujiarui-sketch]

Issue for this PR

Closes #31623

Type of change

• New feature

What does this PR do?

Adds progress feedback to the opencode upgrade command. Users now see real-time progress messages during download and installation instead of a silent process that appears to hang.

Changes:

• New progress tracking types and formatter in src/installation/progress.ts
• Optional progressCallback parameter added to Installation.upgrade() method
• Stream-based download progress for curl method (shows %, size, speed)
• Stage-based progress for all other install methods (npm/pnpm/bun/brew/choco/scoop)
• Integrated with @clack/prompts spinner in CLI upgrade command
• Unit tests for progress formatting

Example output:

[spinner] Checking for updates...
[spinner] Downloading v1.17.0 (45%, 10.0 MB, 2.5 MB/s)...
[spinner] Installing...
[✓] Upgrade complete

Why this works:

• Uses Stream API for real-time progress tracking on curl downloads
• Progress callback is optional for backward compatibility
• Stage-based fallback for package manager methods that don't expose detailed progress

How did you verify your code works?

• Unit tests covering all progress stages and edge cases (15 test cases)
• Manual testing on Linux with curl installation method
• Verified spinner displays progress messages correctly
• Confirmed backward compatibility (no progress callback works unchanged)

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[szzhoujiarui-sketch]

Note: The check-duplicates failure is a CI infrastructure issue (likely OPENCODE_API_KEY or AI service timeout), not a problem with this PR. All required checks pass:\n\n- ✅ add-contributor-label\n- ✅ check-compliance \n- ✅ check-standards\n- ❌ check-duplicates (AI service failure - requests manual review)\n\nThis PR implements progress feedback for opencode upgrade command (issue #31623). Please review manually.

[szzhoujiarui-sketch]

The check-duplicates failure appears to come from the duplicate PR workflow itself rather than this PR code.

Relevant log:

TypeError: undefined is not an object (evaluating 'session.data.id')
at script/duplicate-pr.ts:64:29

The failing step is:

COMMENT=$(bun script/duplicate-pr.ts -f pr_info.txt "Check the attached file for PR details and search for duplicates")

So opencode.client.session.create() returned without data, and duplicate-pr.ts crashes when accessing session.data!.id. This job runs from the base repo workflow/script and uses OPENCODE_API_KEY, so it is independent of the changes in this PR. Please rerun after fixing the workflow/API issue or review this PR manually.