test(honcho): trim salvage coverage to the invariants; drop duplicate ACP session_cwd stamp

Salvage of #93452 (@outpoints). Keep one invariant per fix:
resolver-level "automatic title never remaps a strategy session",
integration "provider routes by logical workspace, not process cwd",
agent-level "title provenance + cwd reach the provider", deferred
Desktop/TUI build threads the session cwd, seeded branch titles are
derived, and the workspace-move E2E. Drop the plumbing/legacy-shape
tests that re-assert the same contract.

acp_adapter: AIAgent(cwd=...) now stamps session_cwd itself, so the
direct assignment after construction was a duplicate.

acp_adapter/session.py

@@ -425,9 +425,6 @@ class SessionManager:
             logger.debug("ACP: bounded MCP discovery wait failed", exc_info=True)
 
         agent = AIAgent(**kwargs)
-        # Codex app-server sessions spawn lazily on the first turn; stamp the ACP
-        # workspace so the Codex runtime starts from the editor cwd, not ours.
-        agent.session_cwd = cwd
         # ACP stdio: stdout is protocol-only JSON-RPC; agent chatter goes to stderr.
         agent._print_fn = _acp_stderr_print
         return agent