fix(pixel-agent-teams): tolerate missing conversation in agent view

[vaibhavsrv]

Why this matters

In ods/extensions/services/dashboard-api/pixel_agent_teams.py, TeamManager.view(row) constructs the external sanitized presentation of team and agent records. When formatting agent review outcomes and retries, it iterates over agent['conversation'] directly:

if agent['status']=='failed' and not any(m['role']=='assistant' for m in agent['conversation']):

If an agent record failed early during initialization (before conversation arrays were populated), was interrupted during serialization, or contains non-dict message entries, accessing agent['conversation'] throws an unhandled KeyError or TypeError: 'NoneType' object is not iterable. This corrupts client status retrieval for the entire team.

This change uses safe dictionary retrieval conversation = agent.get("conversation") or [] and verifies isinstance(m, dict) before inspecting message roles. It also uses safe .get() methods across agent status, role, and retries attributes. Standard completed and failed agent views continue to render identically.

Validation

• Tested baseline reproduction against unpatched code: calling TeamManager.view() on a team row with missing or None agent conversation failed with KeyError: 'conversation' / TypeError.
• Tested post-fix behavior: rows with missing, null, or malformed conversations render cleanly with populated error strings and expected retry flags.
• Telemetry statement: "Dashboard-api suites: 1 passed. New-test Ruff, py_compile, and diff checks pass; new regression wired into Linux CI."

Overlap check

• fix(pixel-agent-teams): guard get result in list to tolerate unreadable history files #5944 (open): Guarded unreadable files in TeamStore.list.
• fix(pixel-agent-teams): validate count range in roles_for resolution #5734 (merged): Validated count range in roles_for in pixel_agent_teams.py.
• fix(dashboard-api): tolerate evicted or missing attempts during pixel chat cancel #5695 (merged): Handled missing/evicted attempts in chat cancellation.
• fix(pixel-settings): reject active token limits exceeding provider capacity #5696 (merged): Clamped active token limits in pixel_settings.
  This PR addresses internal dictionary access safety in TeamManager.view and does not conflict with concurrent PRs.

Risk / AI disclosure

AI-assisted investigation, implementation, and regression test authoring. This hardens view projection safety and does not alter underlying data schemas, controller state machines, or network calls. Independent human review remains a gate.

Follow-up integration evidence

Composed cleanly on top of #5569, #5871, and #5875 at HEAD without conflicts. Production and test diffs passed together; adjacent pixel-agent and pixel-settings checks remain intact.
Backlog composition was local-only (production/test diffs, excluding workflow/Makefile wiring); it is not an upstream merge or independent human approval. Declared live-review gates remain open.