feat(project): wire project-bind side branch into owner creation

[tcp404]

What

Phase 2 of the Project Explorer creation-binding chain (foundation landed in #672). Wires conversation/team creation through ProjectService as a best-effort side branch that starts populating projects / folders / project_explorer and backfills owner project_id / folder_id — without changing any existing behavior.

Design: side branch, never affects existing functionality

• The existing workspace decision (extra.workspace, auto-provision, teams.workspace, agent cwd, delete cleanup, skill symlink) is untouched.
• Binding runs on a side path; any failure is logged at warn and swallowed — it can never break conversation/team create or read.
• Single entry resolve_existing(to_file_uri(workspace)): creates no directory; kind is decided by temp_root (work_dir/conversations → temp, user-picked dir → standard).

Behavior

• create: bind right after the owner row is inserted.
• read: lazy backfill only when opening a single owner — conversation get / team get_team. list / list_teams / lease-renew stay pure reads (no per-row resolve → conversation list and startup session restore stay fast and side-effect free).
• Team member conversations inherit the team's binding naturally (same workspace → same folder → same project).
• IDs via generate_prefixed_id: project_ / folder_ / pe_.

Layering / DI

• aionui-project sits at the Capability layer; aionui-conversation / aionui-team (Domain) depend down on it. Injected as an optional ProjectService (unset → no-op), constructed in AppServices with temp_root = work_dir/conversations to mirror the existing on-disk layout.

DB

• ConversationRow / TeamRow gain nullable project_id / folder_id (+ INSERT / update params). Existing SELECT * / FromRow unaffected.

Testing

• just push gate green: 7426 tests passed, clippy -D warnings clean, fmt clean.
• New tests: create binds (standard + temp), list_does_not_backfill_but_get_does, team create binds, no-op when the service is unset (best-effort contract).
• Existing conversation/team workspace tests unchanged — proving zero behavioral impact.

Refs #672, feat-project-design/formal/bind/wiring.md.