fix(opencode): pass input args to augment hook and allow tool search in subagents

[Chewji9875]

Summary

This PR resolves two issues affecting OpenCode integration:

1. Fix output?.args typo in OpenCode plugin adapter (src/cli/client_adapter.c):
   In OpenCode's plugin API for tool.execute.after(input, output), the arguments passed to the executed tool reside in input?.args, while output contains the result (output?.output). Passing output?.args passed undefined, causing hook-augment to receive an empty payload {"tool_input":{}} and silently failing to augment search results with graph context (Closes Generated OpenCode plugin passes output?.args to hook-augment, so augmentation never fires #1737).

2. Add tool_search and tool_search_regex permissions to OpenCode subagent profiles (src/cli/agent_profiles.c):
   When OpenCode subagents are generated with permission: "*": deny, they were granted read, grep, and glob alongside direct MCP tool permissions. In environments with deferred MCP tool loading (e.g. openstellar-tool-search), OpenCode needs tool_search or tool_search_regex to discover and unlock deferred tools. Adding these permissions enables subagents to unblock graph tools as intended.

Changes

• src/cli/client_adapter.c: Changed output?.args to input?.args in cbm_client_adapter_opencode.
• src/cli/agent_profiles.c: Updated CBM_GRAPH_DIALECT_OPENCODE subagent template to allow tool_search and tool_search_regex.
• tests/test_agent_clients.c: Added assertions verifying input?.args presence and output?.args absence.
• tests/test_agent_profiles.c: Added agent_profiles_opencode_allows_tool_search_and_subagent_permissions test.

Verification

• Ran ./scripts/test.sh --suites "agent_clients agent_profiles" — 49/49 tests passing.
• Verified C binary compilation via ./scripts/build.sh.

[github-actions]

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Current review status: working through a backlog. 0.9.1-rc.1 is out, so the release freeze that held reviews is over — but it left a large queue of open pull requests behind it, and we are reading through them oldest-first. The background is in discussion #1144.

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