fix(tui): show child transcript sessions in resume

[BROCCOLO1D]

Summary

• Makes the TUI historical session picker and most-recent resume path include child session rows that contain the actual transcript.
• Filters out zero-message shell rows and internal tool rows so empty compression/coordination parents do not hide resumable sessions.

Closes #35542

Why

• session.list and session.most_recent queried list_sessions_rich(...) without include_children=True, so transcript-bearing child rows could be hidden while empty parent shell rows were surfaced.
• This made historical sessions look empty even though their messages still existed in state.db.

Changes

• tui_gateway/server.py: request child rows, raw last-active ordering, and no compression-tip projection for TUI resume/list queries; require positive message_count after source filtering.
• tests/gateway/test_session_list_allowed_sources.py: cover the child transcript / empty shell filtering behavior and query kwargs.
• tests/test_tui_gateway_server.py: cover the same behavior for session.most_recent.

Validation

• python -m pytest tests/test_tui_gateway_server.py tests/gateway/test_session_list_allowed_sources.py -q -o 'addopts=' (191 passed)
• python -m ruff check tui_gateway/server.py tests/test_tui_gateway_server.py tests/gateway/test_session_list_allowed_sources.py
• git diff --check

Scope

• In scope: TUI historical session listing and most-recent resume selection.
• Out of scope: broader /sessions vs /resume product semantics or gateway resume scoping changes.

[tonydwb]

Code Review Summary

Verdict: Approved ✅

Review Findings

This PR fixes the TUI session resume path to include child transcript sessions and filter out empty shell rows. Previously, session.list and session.most_recent didn't request child rows, making transcript-bearing children invisible while empty parent shells were shown.

✅ Looks Good

• Root cause: list_sessions_rich() called without include_children=True — child rows with actual messages were hidden.
• Fix: Passes include_children=True, project_compression_tips=False, and order_by_last_active=True to get raw child rows in last-active order.
• Empty row filter: Requires message_count > 0 after source filtering, so zero-message parent shells don't block resumable child sessions.
• Test coverage: 3 test files updated with specific assertions for the new query parameters and filtering behavior.
• Minimal diff: 59 additions, 12 deletions.

No Issues Found

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Reviewed by Hermes Agent

[BROCCOLO1D]

Closing this as stale: there has been no activity or maintainer follow-up for over a week, and I don't want to leave inactive work open. Happy to reopen/rework if this becomes useful.