fix(server): include legacy task states in database list filters

[anxkhn]

description

DatabaseTaskStore can read v0.3 task rows, but its status filter compares their JSON state only with the 1.0 protobuf enum name. A legacy working task is readable with GetTask yet missing from ListTasks(status=WORKING), with an incorrect total.

Match both spellings using the existing compatibility converter. The filter stays in SQL before counting and pagination, with owner scoping unchanged. No schema change is needed.

The regression covers all eight concrete states, mixed modern and legacy rows, missing legacy protocol versions, owner isolation and page tokens. All eight SQLite cases failed before the fix.

validation

Rebased onto main at 799fcae. Fresh checks on that base:

• UV_PYTHON=3.10 ./scripts/lint.sh passed Ruff, formatting and ty.
• UV_PYTHON=3.10 uv run pytest --timeout=45: 2,277 passed, 199 skipped, 3 xfailed, 1 xpassed.
• UV_PYTHON=3.10 uv run pytest --timeout=45 --cov=src --cov-report=term-missing --cov-fail-under=88: same test results, 93.29% coverage.

PostgreSQL/MySQL service tests skipped because their DSNs were unset. The new regressions ran on SQLite. Existing xfail/xpass cases reference #869.

• Follow the CONTRIBUTING Guide.
• Make your Pull Request title in the https://www.conventionalcommits.org/ specification.
• Ensure the tests and linter pass.
• Appropriate docs were updated if necessary. No documentation change is needed for this filter correction.

[github-actions]

🧪 Code Coverage (vs main)

⬇️ Download Full Report

	Base	PR	Delta
src/a2a/server/tasks/database_task_store.py	92.47%	93.01%	🟢 +0.54%
Total	93.10%	93.11%	🟢 +0.01%

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