feat(task): show progress in execution log

[openai0229]

Related issue

Closes #2856

Summary

Add the task's existing progress value to the execution log modal as a compact bottom status strip. The strip keeps the log as the primary surface, shows only the progress bar and percentage, clamps progress to 0-100, and uses semantic success/failure colors without duplicating messages already present in the log.

Affected surfaces

• Frontend / Web
• Backend / API / Storage
• Database plugin / Driver
• JCEF / Desktop packaging
• CI / Build / Release
• Documentation only

Verification

• Commands and results:
  • yarn install --frozen-lockfile - passed; existing peer-dependency warnings only.
  • yarn run lint - passed.
  • yarn test:task-center - passed.
  • yarn run build:web:community --app_version=0.0.0 - passed, including the pre-build regression suite and production-bundle verification.
  • git diff --check - passed.
• Manual verification: Verified in Community Web with a large query-result export. The modal updated while running, reached the 100% success state, retained the log viewport, and displayed the final compact progress-only footer requested during review.
• UI evidence: N/A - screenshots were reviewed locally and are not uploaded because they contain local datasource names.

Risk and compatibility

• Public API or stored data: N/A - consumes existing progress and status task fields.
• Database or driver compatibility: N/A - no database or driver behavior changes.
• Network, privacy, or security: N/A - no new requests or data exposure.
• Community / Local / Pro boundary: Community frontend only; no commercial product code or runtime-mode changes.
• Backward compatibility: Existing task polling, log pagination, virtual scrolling, and task event rendering are unchanged.

Reviewer map

• Start here: chat2db-community-client/src/blocks/ImportAndExport/components/Log/index.tsx for progress/status mapping, then style.ts for the compact footer layout.
• Failure condition: The footer does not update with task polling, displays a value outside 0-100, obscures the log, or repeats task status text.
• Rollback or disable path: Revert commit f15b78e02 to restore the log-only modal.

Contributor declaration

• I linked the Issue that defines this change.
• I tested the affected behavior and reported the actual results above.
• I did not include credentials, private data, or generated build output.
• I disclosed substantial AI assistance below, or this PR contains no substantial AI-generated code.

AI assistance: OpenAI Codex assisted with source analysis, implementation, review, and verification. The maintainer iterated on and approved the final UI behavior.