fix: set meaningful tool titles via tool.execute.after hook

[kuitos]

Problem

All memory tools displayed Unknown in the OpenCode TUI/CLI. For example:

⚙ memory_list Unknown
⚙ memory_search Unknown

Root Cause

Three-layer issue in OpenCode internals:

1. registry.ts hardcodes title: "" — the plugin wrapper that wraps every plugin tool always returns title: "", regardless of what the tool itself does.
2. ctx.metadata({ title }) only affects running state — calling this in execute() writes to the in-progress part, but the completed state is overwritten by value.output.title from the wrapper's hardcoded "".
3. CLI fallback — when title is empty and args are empty (e.g. memory_list takes no args), OpenCode falls back to the string "Unknown".

Fix

Use the tool.execute.after hook, which receives the final output object by reference before it is written to the session part. Mutating output.title there persists into the completed state, bypassing the registry wrapper's hardcoded "".

Changes

• buildMemoryToolTitle() — derives a human-readable title from tool args and per-call result counts
• memoryListCountByCallID / memorySearchCountByCallID — Maps keyed by callID to carry result counts from execute() to the after hook (since memory_list/memory_search need to report how many results were found)
• getCallID() — safely extracts callID from the opaque ctx object
• tool.execute.after hook — sets output.title for all memory_* tools

Verified Titles (end-to-end with openai/gpt-5.4-mini-fast)

Tool	Before	After
memory_list	Unknown	1 memory / 3 memories
memory_search	Unknown	"parallel" · 1 match
memory_save	Unknown	reference: Title Verification Test
memory_read	Unknown	test_title_verification.md
memory_delete	Unknown	test_title_verification.md

Tests

113 pass / 0 fail