feat(opencode-web-terminal): complete OpenCode web terminal implementation

- Update OpenCode compose template with web server on port 3000
- Add default_port=3000 and interfaces=[terminal, web] to OpenCode seed data
- Remove hardcoded 8080 fallback in tunnel creation
- Fail gracefully when tool type has no default_port configured
- Update frontend ToolType API to include default_port, category, interfaces
- Add port, category, and interfaces fields to tool type creation form
- Display port and interfaces in tool type cards
- Create migration 0012 to make default_port non-nullable
- Set default_port values for existing built-in tool types
- Quality gates: typecheck ✓, build ✓, Python syntax ✓

apps/api/src/models/tool_type.py

@@ -19,7 +19,7 @@ class ToolType(UUIDPrimaryKeyMixin, TimestampMixin, Base):
     description: Mapped[str | None] = mapped_column(Text, nullable=True)
     category: Mapped[str] = mapped_column(String(50), nullable=False, default="other")
     interfaces: Mapped[list[str]] = mapped_column(JSON, default=list, nullable=False)
-    default_port: Mapped[int | None] = mapped_column(nullable=True)
+    default_port: Mapped[int] = mapped_column(nullable=False)
     compose_template: Mapped[str] = mapped_column(Text, nullable=False)
     required_variables: Mapped[list[str]] = mapped_column(JSON, default=list, nullable=False)
     is_builtin: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)