Support IBM Bob provider

[ozymandiashh]

Summary

• add an eager ibm-bob provider that discovers IBM Bob IDE task folders from both the GA IBM Bob app data directory and the preview-era Bob-IDE directory
• reuse the shared Cline-family task parser for Bob-compatible ui_messages.json records, while adding provider-specific multi-base discovery and ibm-bob-auto fallback pricing/display
• parse api_conversation_history.json model tags when present, use Bob-reported costs when available, and otherwise calculate cost through the configured model pricing fallback
• wire IBM Bob into provider registry, dashboard colors/display names, macOS provider tabs, package keywords, README/provider docs, architecture docs, changelog, and provider icon assets
• add focused tests for discovery, missing ui_messages.json, token/cost parsing, model fallback, deduplication, and metadata/display names

Closes #248.

Notes

• This intentionally supports the IBM Bob IDE task-history surface: User/globalStorage/ibm.bob-code/tasks/<task-id>/.
• IBM Bob Shell checkpoint data under ~/.bob is left out of scope until there is a stable usage schema fixture; parsing it now would risk reporting misleading usage.
• Existing Roo Code and KiloCode behavior is preserved because the shared parser keeps the same public call shape and defaults the fallback model to cline-auto.

Validation

• npm run build
• npx vitest run tests/providers/ibm-bob.test.ts tests/providers/roo-code.test.ts tests/providers/kilo-code.test.ts tests/provider-registry.test.ts (4 files / 34 tests)
• npx vitest run (48 files / 668 tests)
• swift build
• git diff --check
• Argus local reviewer: PASS
• Claude Opus 4.7 effort max: PASS
• Gemini 3.1 Pro Preview: PASS

Known Local Test Note

• swift test still fails on the existing unrelated local Swift toolchain issue in mac/Tests/CodeBurnMenubarTests/CapacityEstimatorTests.swift:2:8 (no such module Testing).