feat(install): improve logging, error handling, and bulk-loop resilience

[tankdonut]

Summary

Improves the tools.install task with better verbose logging, resilient bulk installs, and clearer error context.

Motivation

A review of tools.install found that: (1) one package failure aborted the entire bulk install, (2) download errors lost package context, (3) there was no --verbose mode or per-step status, and (4) the output style was inconsistent with the update/digests tasks. This addresses all four.

Changes

Logging & verbosity

• --verbose flag on tools.install: echoes underlying shell commands (curl, tar, chmod, etc.) and shows curl's download progress meter
• Switched the downloader's print() to logging.getLogger (info for download/verify steps)
• Task layer uses rich.console (OK/SKIP/✗) for consistency with update.py and digests.py
• Added [i/N] installing <name> progress header for bulk installs and a final Summary: X installed, Y failed

Error handling

• Bulk install no longer aborts on a single failure — failed tools are collected and reported; remaining tools continue. Exits non-zero (Exit(1)) if any failed
• Download errors wrapped with package name + URL: Failed to install '<name>' from <url>: <cause>. IntegrityError passes through unwrapped (already carries context)
• check_required_tools error now names the package that needed the missing tool
• --force removal switched from c.run('rm -rvf ...') to shutil.rmtree (removes a shell-interpolation surface)
• metadata_cache.clear() moved into a finally block so it runs on success or failure

Integrity visibility

• The downloader now logs a WARNING (always visible) when a binary is installed without an sha256 digest configured, rather than skipping verification silently

Files changed

• tasks/lib/downloader.py — verbose/echo support, logging, verify-step visibility
• tasks/tools/_install.py — package-context error wrapper, verbose passthrough, shutil.rmtree, rich console output
• tasks/tools/install.py — --verbose flag, resilient bulk loop, summary, finally cache clear
• tests/test_install_task.py — 10 new tests (error wrapping, IntegrityError pass-through, verbose passthrough, force removal, already-installed skip, bulk-loop resilience, cache-clear-in-finally)
• tests/test_sha256.py — updated fake_run signatures to accept the new echo= kwarg

Verification

• ruff check + ruff format --check — clean
• pytest — 164 passed (+13 new tests)
• Coverage: _install.py 95%, install.py 94%

Checklist

• Tests added for new behavior
• Lint and format clean
• No new dependencies introduced
• No public API removed (check_required_tools gained an optional param; install_single_package gained optional verbose)